Thanks for indulging this newbie. After a lot of study on this forum I've
reformulated my question with much more data after continuing to have the same
issue.

Site: www.vhlcentral.com; After logging in normally, I land here:
www.vhlcentral.com/home; then after clicking on the link to "my" book, I land
here:
<https://m3a.vhlcentral.com/sections/0/programs/145?ticket=ST-1608944208r622112FC86D9E1FFC7>,
which is where the lessons start. 

On the mirror, I cannot get past the login page even though I included the
URLs listed above(& the download only lasted for a few minutes so there's not
much data there) even though I filled in my username/PW per the instructions
when entering the URL. I don’t know what the “assets.maestro” folder is,
as I don’t see that in a URL when normally browsing. I suspect it has
something to do with “teacher” access. When I tried eliminating the folder
for that using “- *” I no longer got the "Forbidden" (403) errors but same
as before, all I get is the login ‘landing page’ and cannot navigate from
there (if I put the password in on that page, I only get an error page on
VHLcentral’s site.). 

Here are my winHTTrack settings:
Flow Control: One connection
Browser ID: msie6
Links: "get non-html related files"; "Attempt to detect all links"; 
Limits: External pages: "0"; Max connections/seconds set to "1"
Flow Control: Time out = 60; Retry = 9

Log File: (note, I've replaced my real login/password with LOGIN:PASSWORD).
I'll include the first few lines and the closing lines so hopefully this will
give enough data. All the "Forbidden" (403) lines in the middle are pretty
similar but if someone would like to see it, I can include it in a follow up.
So, here it is: 
HTTrack3.49-2+htsswf+htsjava launched on Fri, 25 Dec 2020 17:26:45 at
<https://LOGIN:PASSWORD@www.vhlcentral.com>
<http://LOGIN:PASSWORD@www.vhlcentral.com/home>
<http://LOGIN:PASSWORD@m3a.vhlcentral.com/sections/0/programs/145?ticket=ST-1608944208r622112FC86D9E1FFC7>
+*.png +*.gif +*.jpg +*.jpeg +*.css +*.js -ad.doubleclick.net/*
-mime:application/foobar +www.vhlcentral.com/home*
+m3a.vhlcentral.com/sections/0/programs/145?ticket=ST-1608944208r622112FC86D9E1FFC7*
(winhttrack -qw%e0C2%Pns2u1%s%uN0%I0p3DaK0c1T60R9H0%kf2A50000%c1%f#f -F msie6
-%F "<!-- Mirrored from %s%s by HTTrack Website Copier/3.x [XR&CO'2014], %s
-->" -%l "en, *" <https://LOGIN:PASSWORD@www.vhlcentral.com>
<http://LOGIN:PASSWORD@www.vhlcentral.com/home>
<http://LOGIN:PASSWORD@m3a.vhlcentral.com/sections/0/programs/145?ticket=ST-1608944208r622112FC86D9E1FFC7>
-O1 "D:\WinHTTrack_mirrors\escuala_de_espanol3\vhl_escuela" +*.png +*.gif
+*.jpg +*.jpeg +*.css +*.js -ad.doubleclick.net/* -mime:application/foobar
+www.vhlcentral.com/home*
+m3a.vhlcentral.com/sections/0/programs/145?ticket=ST-1608944208r622112FC86D9E1FFC7*
)
Information, Warnings and Errors ... if you want these information to remain
private
17:29:12 Error:  "Forbidden" (403) at link
assets.maestro.vhlcentral.com/assets/music/icons/check-651aace7e9b5960145d405501c81bc26d4537c5b396b584957c41e3226b4e9bd.svg
(from
<https://assets.maestro.vhlcentral.com/assets/music/library/v1/main-c5c5be5e459e62499f29e2a00c479eaef85ba12618ce711ef704d3eb018860f1.css>)
17:29:12 Error:  "Forbidden" (403) at link
assets.maestro.vhlcentral.com/assets/music/ui/navigation-arrows/icon-circle-arrow-394bb15de408115540f26bc5059fdfd0456caa3d1bf875b395ab76ae28c43e4b.svg
(from
<https://assets.maestro.vhlcentral.com/assets/music/features/masthead/main-a7db78d04e99d224a629945221b978125992b54deb917c1f03a23a1b8935f392.css>)
...  ...  ...  ... closing lines>
17:29:40 Error:  "Forbidden" (403) at link
assets.maestro.vhlcentral.com/assets/account_menu_divider-3c4c519a3f65cc06c708f67411f7ad7d4216e7f881a18b51ddff2e978742ca6a.png
(from
<https://assets.maestro.vhlcentral.com/assets/layout-2a2c32d6c8c3d1fd28f2d85ec7944c6d9518bc56b0314cce7ac88e198170fcc6.css>)
17:29:40 Error:  "Forbidden" (403) at link
assets.maestro.vhlcentral.com/assets/toc_hover_arrow-0abbbd8c907542e63f84ef30a6900461cab677ed67f07821708292bc3bb8e57e.png
(from
<https://assets.maestro.vhlcentral.com/assets/application-0f839152533f2a900a6fb892a85d8ab7497426d1bca31b09ad4e4478d0af240f.css>)
17:29:40 Error:  "Forbidden" (403) at link
<https://assets.maestro.vhlcentral.com/assets/resetbase.css> (from
<https://assets.maestro.vhlcentral.com/assets/screencasts-229ebb226c400089f3d79fe1f4e2b7c6cdeea46abfc138073d5331415c447e47.css>)
17:29:40 Error:  "Forbidden" (403) at link
<https://assets.maestro.vhlcentral.com/assets/components.css> (from
<https://assets.maestro.vhlcentral.com/assets/screencasts-229ebb226c400089f3d79fe1f4e2b7c6cdeea46abfc138073d5331415c447e47.css>)
17:29:40 Error:  "Forbidden" (403) at link
assets.maestro.vhlcentral.com/assets/bkgd-form-field-10ecbad08e66ed61b37c8f7f76a6df4c293240f68fa38680696761b3a65c2848.gif
(from
<https://assets.maestro.vhlcentral.com/assets/full_width_content-fd6985303086c128a17b79fec1f6a271eb473118a2036fef113d6c176062cce9.css>)
HTTrack Website Copier/3.49-2 mirror complete in 2 minutes 55 seconds : 76
links scanned, 49 files written (5791650 bytes overall) [2769168 bytes
received at 15823 bytes/sec], 4092689 bytes transferred using HTTP compression
in 34 files, ratio 24%, 2.8 requests per connection
(24 errors, 0 warnings, 0 messages)

So, this is an electronic textbook which is going to go away in about 30 days
and I would really like to have it, to continue my study of Spanish at my own
pace since I am already familiar with its format, etc...

I hope someone can help.

Thanks in advance,
Brian