After downloading the mod, use a program such as 7zip or WinRAR to extract the main folder of the mod.
Move the main folder of the mod to assets/mod_overrides. The assets folder is supposed to be in your game's installation folder (don't know where that is? click here for PAYDAY2 folder). Create the folder if necessary
To install:
Go to the folder where Payday 2 is hosted (You can also go to steam, right click the game via library, click properties, click local files, then click browse)
Navigate to PAYDAY2/assets/mod_overrides (Create a folder named "mod_overrides" if it doesn't exist)
Extract the "Vibri Cloaker" file from Vibri Cloaker.zip, and place it into the mod_overrides folders.
Any addition mods that replace the cloaker's voice lines or charging sound might cause problems