If you are unsure I would look for a shop in your area that is comfortable working on Subarus. It's not painfully difficult and there are hundreds of how to videos on YouTube so if you want to take a stab at it you should be fine.
There are a few common leak points, including factory top mount around the plastic end caps, turbo inlet, intercooler to throttle body hose, the tumble generator valves, as well as the turbo to intercooler connection.
Is the car modified at all? You mentioned you had to borrow an ap to read the codes. However if there is any modifications like an intake, turbo back exhaust or upgraded top mount getting the tune will be the top priority as it can cause misfires and engine knock that will kill the engine dead.
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