Windows Server 2019 Create Iso From Folder

Thanks, chuchoamezcua! It indeed seems to have something to do with special characters in the file path (i.e. from the my user account name). I was copying the installer executable to the Desktop but it didn't work (because the file path still had my user account name in it). I copied it to C:\ and it worked from there. It seems to be a bug in the installer, then.