Required mods:

1. ScriptHookV
https://www.gta5-mods.com/tools/script-hook-v

2. ScriptHookVDotNet
https://www.gta5-mods.com/tools/scripthookv-net

4. LATEST Map Builder (REQUIRED)
https://www.gta5-mods.com/tools/map-builder

Install:

1. Run OpenIV

2. Drag and drop the folder billionairemansion in the following path: mods/update/x64/dlcpacks

3. Go to: mods/update/update.rpf/common/data, open dlclist.xml and add the line which can be found in the zip (read me) file.

4. Install Free Map builder (Required)
https://www.gta5-mods.com/tools/map-builder