Halo Waypoint isn’t currently connected to Halo 4 File Shares. So, the gametypes and maps you need for the AGLA will have to be found directly on Halo 4 by searching through our File Shares.
Official Gametype & Map
Gametype: A.G.L.A. Grifball WL13
Map: A.G.L.A. Foundry
Download from any of the following File Shares on Halo 4: