rFactor 2 relies heavily on a "package" system. If the game detects a mismatch between your files and the official server files, you will likely be unable to join multiplayer sessions or competitive leagues.
Most unlockers operate by modifying or replacing specific Dynamic Link Library ( .dll ) files within the game's directory. rfactor 2 dlc unlocker
Install script for installing DLC content to rFactor 2 ... - GitHub rFactor 2 relies heavily on a "package" system