CorkscrewRules CoOp v1.2.6 (standalone/server) file

First of all subscribe or download workshop files from:
Steamcommunity.com

Extract archive to main game directory

Example: C:\Games\Steam\steamapps\common\POSTAL2Complete

to start the game:

1) open C:\Games\Steam\steamapps\common\POSTAL2Complete\System

2) start Postal2CRCoOp.exe

3) enjoy the game

All information about joining and hosting:
Steamcommunity.com

to start dedicated server:

1) open C:\Games\Steam\steamapps\common\POSTAL2Complete\System

2) open Postal2CRCoOp_RunServer.bat

3) join game with Postal2CRCoOp.exe

More info about server:
Steamcommunity.com