Download the specific "FIFA 21 JTAG/RGH" mod files from a trusted community source.
Sometimes, the modded assets are recognized by the console as unpurchased or corrupted DLC. Launch on your Xbox 360. Mod FIFA 21 -Jtag RGH-
While Jtag/RGH consoles are offline by nature (if you are smart), mistakes happen. Download the specific "FIFA 21 JTAG/RGH" mod files