Where can you borrow e-books for adobe digital editions?

netlibrary.com is one place, but only if your public library is set up with them.

Check your local public library for eBook options. There are several services that libraries offer, including Overdrive, 3M Cloud Library and Axis 360 to name just a few. You can check out ebooks from participating libraries using your library card. Many eBooks are loaned to one person at a time (similar to a paper copy of the book) so you might need to put a reserve or hold on the title you are interested in. Also be aware that not all publishers license eBooks for library lending so the bestseller that you are interested in may not be in your library's collection. there are thousands of eBook which are available through libraries and this is a great and convenient way to expand your reading options.