> -*.jpg
> -*.gif
> +/*filename
> +/*filename
> 
> When I run the mirroring HTTrack downloads other zip files
> that do not match the filename inclusions above.

This is normal: there are some "default" filters defined. 
For example, if you start from 
www.foo.com/bar/
then the following filter will be inserted as first filter:
+www.foo.com/bar/*

Hence, you have first to exclude all zip files, and then 
authorise desired ones:

-*.zip
-*.jpg
-*.gif
+/*filename
+/*filename