I tried deleting everything ugx and the map to try it again, and I can read the error message now at least. "Unknown object "zombie_colt". I've looked at posts from people who got this error too, but none of the solutions worked. Any idea what to do?

thats usually down to a problem installing the mod tools in the first place

could also relate to _zombiebmode_weapons.gsc as that may call a precache

or anyother place that weapon gets precached ( laststand for example )