Huge miles per year, find out where owner has had it serviced, how often and specifically check if timing belt and head gaskets been replaced. These are common big dollar issues for the 2.5 liter flat 4 that powers the Forester; bet it's the same engine. Luck.
If it has a CVT be aware that parts are not available. Should it fail you'll have to either source a used one and hope it's okay or cough up ~$8k for a new transmission. I'd definitely have the fluid replaced asap unless there is evidence it has been done recently, but this may cost up to $800 if done by a dealer. A manual would, imho, be a better bet.