UE4.27.2 refusing to compile from source

Hello. I’m trying to compile UE 4.27.2 under Linux but it simply refuses to work.

Following Epic’s own guide, I can get as far as running setup.sh, but when I try to run GenerateProjectFiles.sh, it just returns with “GenerateProjectFiles ERROR: This script does not appear to be located in the root UE4 directory and must be run from there.“, even though the file is in the directory.