Even with a fixed key, standard in-game matchmaking is generally non-functional due to the decommissioning of official servers.
Post-remediation actions
Share your own method for fixing the GRAW multiplayer ID key in the comments below. Ghost Recon Advanced Warfighter Multiplayer Id Key Fixed
The installer asks for a Multiplayer ID but immediately errors out or won't accept a valid key. Fix: Go to Windows Security > Virus & Threat Protection . Even with a fixed key, standard in-game matchmaking
(If you’re on 32-bit Windows, drop the WOW6432Node part) Even with a fixed key