Install:

Single Player:
Using OpenIV
-Copy infernussa folder into mods\update\x64\dlcpacks
-Add: dlcpacks:\infernussa\ to the file dlclist.xml in mods\update\update.rpf\common\data
-Spawn name: infernussa

Fivem

Copy folder infernussa inside 'fivem' to your server resources folder, add 'start infernussa' to your server.cfg
spaw name: infernussa