The requirements will vary between companies and they should always be consulted directly, however some things to consider when renting a vehicle for your stay are:
Driving licence- You will need a current, valid Driver’s Licence, held for a minimum of one year and any necessary international driver's permits.
Age Restrictions- There may be minimum age restrictions to rent a vehicle. The minimum age requirement varies depending on the vehicle and pick-up location.
Mileage Policy- You may be required to estimate your mileage and fees may apply if you exceed this estimate. It is for example a 75 mile journey from Aberdeen Airport to Grantown.