If you are installing DAMASK for linux (i.e., not ios), there is an installation guide under DAMASK/private/documentation/DAMASK Install guide.pdf which might be of help.
Thanks Aritra. Actually, we did not find the path you mentioned "DAMASK/private/documentation". That is we did not find the "private" directory. If possible can you please send me the pdf,
If you are using Linux or macOS, open your .bashrc or .bash_profile file and add the variable PETSC_DIR to the file with the path of the PETSc that you want to use