I am not sure if this is helpful in your case or not but...A real epub you can use a zip program like the free 7zip from
7-zip.org and extract them into their various folders. I have extracted embedded MP3 files and fullsize images this way from some of my guitar ebooks. You can even get access to the CSS files. It's basically a compressed zip file.
I don't know what your ALEKS textbook is though...
Basically select the ebpub file and right click on it and select extract from your flyout menu in Windows...this is assuming the archive program you have installed has their file associations integrated into Windows Explorer.
This goes into more info...
https://www.techwalla.com/articles/how-to-extract-epub-files