You must pick up your card in person. You're going to have to sign the waiver anyway.
Note that to pick up your ID card, you will need:
17 and Up:
Valid Government Issued Photo ID (Driver's License, State ID, Passport, Military ID)
16 and Under:
Valid Government Issued ID OR
School Photo ID with birthdate OR
School Photo ID with birth certificate OR
School Yearbook with birth certificate
You may substitute a driver's permit with your birthdate for a birth certificate.
No other forms of identification are acceptable, and if you do not have acceptable ID, you will not be able to pick up your PSP ID Card, and without a PSP ID card, you won't be able to play. So remember to bring your proof of ID, it's just as important as your marker!