OK, just booted it up from the folder to check and it launched just fine. It's odd, I've launched a bunch of UE stuff from itch just fine, including my own stuff. Not sure what's causing that.
Moonshot option: SteamVR is launching automatically when the game starts. This is default behavior for a UE project, but I wouldn't be surprised if something got stuck waiting for SteamVR to launch when it didn't need it. You can disable the SteamVR plugin on your project and it will stop that from happening.