FIFA 21 Crashes at Startup
The first thing you can try is whitelisting FIFA 21 from your firewall and anti-virus and check if the crashes stop. If the issue persists then try running the game on windowed mode. To do that, you can either rename the game’s shortcut target to -w, hit Alt+Enter when the game boots up, or edit the .ini file to run on windowed mode.
Crashes at startup could also be related to the GPU drivers being outdated. Check whether or not you have any pending updates. Install them and then try launching the game. Try running the game with Administrator rights too.