version changes with windows 10

I have a 6 month old windows 10 laptop that I use only for specific tasks including downloading ebooks to adobe digital editions.

I last downloaded a library book in December to ADE 3 no problems.

I recently tried to open ADE 3 and was told it needed a windows net update which I tried 4 times to download and install without success.

I therefore uninstalled ADE 3 and installed 4.5.

I now cant download books purchased from kobo.

I successfully downloaded them onto an old computer using an old version of ADE.

3 questions:

what has happened to ADE 3 that it will no longer work on my laptop?

why doesnt ADE 4.5 seem to work at the kobo store?

why doesnt adobe offer any support for ADE?

any advice gratefully received.