It means you have file conflict!
Try this using OpenIV
Go to: mods/update/x64/dlcpacks/sheriffpack/dlc.rpf/common/data
you need to edit carcols.meta & carvariations.meta
in carcols.meta :
1) serach for <id value="15"/>
change the value 15 to any number e.g. 150 (must be above 20s)
2) search for <id value="17"/>
again, change the value 17 to any number e.g. 170 (must be above 20s)
save and replace.