I literally can't get in the lobby. When I try it gives me an error or flat out makes me crash. I've reinstalled the game from scratch 5 times

Warhammer 40,000: Darktide Technical Support
8

The crash data prints an error where it seems to think you’re not running Windows 10. Do you have the latest Windows 10 updates installed?

This error is also tied to DirectX 12, so I recommend a clean re-installation of your GPU drivers too: