So… i had a similar issue, i would start the game, once the game window popped up POOF! Fatal Error. i tried everything, directX, GPU drivers, visuals, reinstall, even a clean windows install and everything i found in different forums.
I Dont suggest messing with files but hey, this worked for me after 2 days. Could just be coincidence but try this…
Possible solution:
1:Go To: Program FIles (x86)>Steam>steamapps>common>Conan Exiles>ConanSandbox
2: Once inside delete EVERYTHING EXCEPT the Content folder (keep Content NOTHING else! The size of Content is ~100gb (Conan Exiles/ConanSandbox/Content)).
3: Once they delete, Verify Integrity of Game Files. Then wait some time for it to download the couple GB of stuff back.
4: Try running the game once it finishes, and pray.
I hope this helped for at least someone and not just me. Sorry if this is useless otherwise… NO idea why this worked when a fresh install of the game didnt…