The process makes file to read via http (not https), it’s just a nonce ( some random characters). Once their server reads that file, using the domain (and not the ip) and compares with what is expected, this shows you own the domain , and they give you a new ssl cert, modifying your server’s https configuration file (usually). And deletes the file it made .
I think the reason I switched back was because my computer was underused - a lot of the memory was free and the fans hardly ever came on, except when gaming.
But now windows uses every bit of my ram, filled up my hard disk and the fans are humming along.
Thanks Microsoft!!