I need to know about the Z Visa and PU Letter

I have already applied for my z visa and could not use it due to the lockdown from March. I now had to reapply for my police clearance that had expired. My school is in the process of applying for my new work permit. Can I take my police clearance to the Chinese consulate without the PU Letter or is the PU Letter compulsory? It would also be appreciated if you can advise on the process thereafter at the visa office.