This is mostly a reminder post for me but it might also help others with MAC OSX 11.5 (El Capitan) solve the same problem I had.
When trying to RDP to a windows 10 computer from my Mac Book I was getting an error along the lines of “Remote Desktop cannot verify the identity of the computer you want to connect to”
It’s a fairly useless error message. And it took quite a bit of searching for a working solution. Fortunately Stack Exchange came to the rescue with this answer
Follow through the steps and you’ll be good to go.