An InPrivate browser window in Edge is a special browser window that ignores your cache and cookies, and which does not save your history. You can open one through a menu option or by using Control-Shift-N.
I did delete all browsing, cookies, cache etc. which is a HUGE pain because now every site I went to, banks, stocks, credit cards, email I had to do the '2 step, send me a link through email or phone text' to sign in on...
That is one reason I rarely suggest deleting all cookies; generally that is not necessary. Deleting just your eBay cookies would likely have fixed your issue without having to sign back in to all those other sites.
...but I got through it and most important, it worked. I can now sign in using Edge.
Excellent!
Likely there was a problem with your eBay cookie. Possibly a change in eBay's page lead to a condition where the site data and cookie data were in conflict. Normally when that happens the old data is overwritten by new data and everything keeps working as expected, but once in a while the old data is not overwritten and there are problems. That is when erasing a cookie can be helpful.
