INSTALLATION is as follows;

[Vehicles]

1. Start OpenIV.
2. Go to the 'mods' folder, create one if you don't have one.
3. Drag the LSPDBeach folder to mods\update\x64\dlcpacks
4. Find dlclist.xml - It's located here mods/update/update.rpf/common/data
6. Edit the dlclist.xml and add <Item>dlcpacks:\LSPDBeach\</Item> at the bottom

[DLS Configs]
Drag the xml files provided to Grand Theft Auto V\plugins\DLS.