if it's a roof leak then the gasket is not tight or not installed correctly. You can find the hold downs by removing the inside cover. First pop out the filter, there may be a couple of screws accessible there as well as two round plugs that cover the others. The cover attaches to the interior frame, once removed you should see four long bolts that attach the inner and outer frames and squeeze the roof via the foam gasket, that's probably where it's leaking. Try cinching them down a couple of turns but do it evenly so the gasket is compressed equally.
If it leaks during operation then you'll need to inspect the condensate drain on the roof, requiring roof access and removal of the outer cover; look for debris in the pan or drain line.