Asi Loader is essential because it allows you to launch. If it does, we'll update this guide, but you're stuck with vanilla GTA 5 until then. Unfortunately, Script Hook V hasn't been updated to support the Epic Games version.
If you're playing the game through Steam, this can be found in \SteamApps\common\Grand Theft Auto V\.
Copy ScriptHookV.dll to the parent GTAV folder.
