So chances are you wanted to play this excellent mod but it crashes when you try to play it via steam. You can still play the mod by using the version from ModDB here: https://www.moddb.com/mods/happy-night/downloads/p2-happy-night-delete-edition-v-15
Now this version works great... except for one thing. There is a mission where you need to race a taliban on a sled and when you try to ride the sled nothing happens causing a soft-lock as you are unable to leave and no-clipping to the finale does not complete the task.

So it appears as everything is good again. To play this mod just revert your postal 2 version to 5023 by right clicking on the game>properties>betas>opt-in to 5023 and THEN download the mod.
The steam version does not have the issue with the taliban race.
This post was made back when nothing worked and only the ModDB version ran at all.