Onedrive keeps asking for email after I type it correctly for ransomwa

After the recent Windows 10 update, Microsoft security program prompted me to set up Onedrive for ransomware protection. I click on set up, a pop up opens to enter my account e-mail. I'm entering the e-mail I'm using for my Windows account. The one that is associated with my user account on my pc.

After I type it and continue same pop-up comes up again and empty. I hadn't used Onedrive for a long time. I had to unfreeze it. I logged in to Onedrive after unfreezing from my browser as well but the ransomware set up still doesn't work.

How does this ransomware protection work anyway? Is it just storing important files online? Does it backup system files automatically or do I backup my personal files myself?

Last question: Is ransomware the malware that deletes your files unless you pay the hacker money? Do these come from shady ads?

Thanks for your time.

I haven't used OneDrive to this day. I think my account was frozen because of that. I had removed it from startup too. I'll look at some tutorials you linked to see in case I need to enable something.

edit: Thanks. I used the first link to set up OneDrive through system tray icon. Settings and Add an account. This brought up the same pop-up that wasn't working but this one worked. Later I could set up Windows Security to use OneDrive and the warning is gone.