I just tried running on Arch linux and was greeted by this error:
"vulkan device could not be created at the project's supported feature level"
There are some console warnings but I don't think they're relevant:
(zenity:113424): Gtk-WARNING **: 11:26:22.021: Locale not supported by C library. Using the fallback 'C' locale. (zenity:113427): Gtk-WARNING **: 11:26:22.081: Locale not supported by C library. Using the fallback 'C' locale. (zenity:113427): Adwaita-WARNING **: 11:26:22.169: Using GtkSettings:gtk-application-prefer-dark-theme with libadwaita is unsupported. Please use AdwStyleManager:color-scheme instead.
I can't seem to find any error logs. I tried both using my in-built Intel GPU and my nVidia GPU. Maybe you need to lower the feature levels (whatever those are) in Unreal?
Also when I unzipped it unzipped to a folder "Linux". Better would be if it was called "CrabLegs" or "CrabLegs-Linux" or something.