Help - Adobe Digital Editions 4.5.6 will not download my books

Over a week - not that computer literate but been on a forum and being helped so much but not getting anywhere.

1. Have made sure all Windows 10 - up todate  (Grasping at straws in case something was clogging up system)

2. Have deleted all books on files?

3. Checked 'Choose Default Apps by File type' - all OK for ADE

4. Deleted ADE and restarted laptop - with fingers crossed.

5. Went to Library downloaded book and up comes this screen for ADE basically wanting to download program again!

Gone are the days when I could just choose my book, download - see ADE open with book downloaded across - plug in KOBO - move across - happy days!

Thanking you in anticipation that someone else has had this frustrating time consuming problem and can help me.

P.S. I have just read on here, i think my brain is all over the place now, that you can try downloading from Library in ADE.  So I searched where it should be and looked in my computer -

6. Under Documents - Adobe Digital Edition - clicked on but the book I just downloaded isn't listed. Others have but they have a symbol with a BLUE -e  is that correct?  Is that a clue to what is going wrong?

UPDATE!!!!

Went onto old laptop (Win 😎 and see re: point 6 above the Blue e - is a ADE icon.  Went into properties of a book and it says 'open with Microsoft Edge - I clicked and said Chrome (I think) anyway they all came back up with ADE Icon.  Sooooo I think Microsoft Edge is trying to get in there somewhere - don't understand this!!!

Anyway tried downloading another book thought i had cracked it - but up came the window to download ADE again!!!