This unlock pack contains a savegame with everything unlocked:
Unlocks all cars, all tracks, all regions, all rewards, rank 30
And one savegame which just unlocks all cars
Install: Copy the savepool.xml of your choice to
"Steam Directory\UserData\UserID\202310\local\Ridge Racer Unbounded\Autosave.bin\"
XP: "User Profile\Local Settings\Application Data\SKIDROW\202310\Data\Ridge Racer Unbounded\Autosave.bin\"
Don't forget to make a backup of your current savegame!