I found the problem:
The readme says to put <Item>dlcpacks:\addonpeds\</Item> at the end of dlclist.xml but this is a formatting error.
You should put <Item>dlcpacks:/addonpeds/</Item> instead.
Or, simply change the two \ to /
If you look at all the rest of the lines above it they all have /
I also already had installed the three addons mentioned by jfosterbraves1 above located at
https://www.gta5-mods.com/misc/gta-5-gameconfig-300-cars so I am not sure if those are needed or just fixing the \ to / will help you
I found the problem:
The readme says to put <Item>dlcpacks:\addonpeds\</Item> at the end of dlclist.xml but this is a formatting error.
You should put <Item>dlcpacks:/addonpeds/</Item> instead.
Or, simply change the two \ to /
If you look at all the rest of the lines above it they all have /
I also already had installed the three addons mentioned by jfosterbraves1 above located at
https://www.gta5-mods.com/misc/gta-5-gameconfig-300-cars
so I am not sure if those are needed or just fixing the \ to / will help you
But I'm running around as Superman right now...