I have the same issue. I have a Mac Book pro 13 inch, i am ready to throw it in the trash, I downloaded Big Sur and nothing works. 4 hours to download, another 2 hours before I could use it and even while typing this it is crazy hard because of the jumpyness and type disapearing. I am not super tech savy which is one of the reasons I went with Mac it was always so reliable. I don't know what to do this computer is not useable as is. I can not open or reply to an email. Also can not open about this mac???? I do not understand hope they can fix this