You will need 2 pairs of M3 bolt and threaded insert. I believe you can actually get away with a single bolt, but 2 is rock solid.

Mine is printed in PETG and isn't going anywhere, track tested!. I believe PLA should do the job as well.
Multimaterial supports really help with the cleanup of the quadlock slot, but it's doable with traditional supports, just expect a lot of manual cleanup.