Help! Crashes on start up - steam :(

My game starts up just fine and I have an rx570 gpu. My husband has a gtx970 however and has tried all possible fixes. It will load for about 30 seconds, he’ll hear the iconic music for three of those seconds and it will immediately crash from there. We’ve tried renaming the txt file, he moved the files over to his c drive, there are no programs running in the background, and drivers are all up to date. Please lmk if there are any other fixes to this problem! I just want to play Halo w the hubby!