For anyone who's trying to get the Mexican PCC and who lives in Mexico.
1 - E-mail
MXICO-IM-RAU@international.gc.ca once you receive a request from IRCC and ask them for a letter addressed to the PGR.
2 - Book an appointment with PGR once you have this letter - the visa office sent me the letter within couple hours.
3 - Bring all the documents stated in the PGR website (passport, birth certificate, photos, etc). They will take the fingerprints there.
4 - You'll get a receipt which says that you'll get the PCC within 10 business days but I got mine in 4.