This is probably not the appropriate subforum for the question. It might be better in the main Kindle/amazon forum or even calibre forum.
BUT, big BUT... no one can provide specific instructions to do the required removal of DRM (the coding that locks up epub (generally) library books (which is different than the drm on Amazon's own books)
But first you need a library account, then you need to download the reader application that actually allows attaining and reading the books on your computer. One thing - most of what you initially download from a library is a token for the book download and not the book. It is a small acsm (or some mix of initials) file. The reader program uses that to actually get the book.
Then you need to explore Apprentice Alf blog, particularly the comments or use a search for "Tools" or perhaps "3.1" And, yes, it does involve python but readme files will show the way. Not always simple.
Or you can get a Sony or other epub-able reader.