Paste your XUID hex code into the tool to "re-sign" the save for your account.
A high-quality 100% save file usually provides a complete sandbox experience with everything already unlocked:
: Copy your original User Profile folder or profile.data file to a safe location.
Every race completed, all barn finds discovered, and every PR stunt cleared with a 3-star rating.
: \userdata\ \1551360\remote\ \ .