Permission denied when updating to big sur
I'm trying to update to Big Sur, because I thought it would help fix an issue with my contacts. But when I got to install it I get an error saying I don't have permissions. I've tried on three separate admin accounts, one made just for this. And still got the same error when I went to the get info part for the drive labeled Macintosh it says admins are read only and only the system has read and write. I also went into my settings and made sure the install big sur app had permissions. I'm not sure what else to try.
MacBook Air 13″, macOS 10.15