I have two fixtures, a PVC pipe and a (3D Printed) socket made out of PLA that I would like to mate. I made a trip to the hardware store and was intimidated by the selection the fact that most cautioned against using on plastics. What kind of adhesive (and I'm not picky to glue, putty, epoxy or cement etc) do I specifically need?
Beware that if in a use that is subject to plumbing code, your 3D printed item almost certainly will be a code violation.
The probable best bet (and I'm not guaranteeing success) would be a "Multipurpose plastic pipe glue" - go to the plumbing section, find the PVC pipe cement, don't buy that - look for the somewhat smaller stock of pipe cement that claims to work on PVC, ABS, and perhaps a few other variants of plastics - try that. Use PVC pipe cleaner and primer on the PVC side of the joint. Make some test joints and try to tear them apart after they have had a day or two to cure.
If, as I vaguely gather, PLA is essentially the most common form of hot glue, then judicious and careful use of a hot glue gun would be the other option that might work.
I've had success gluing a printed PLA part to PVC using a glue from Selleys called All Plastic Fix. It's a two step procedure where you use a priming pen/marker on both areas to be joined then simply apply the cyanoacrylate glue to one side and hold pressure on the join for around 30 secs.
The resulting bond is very strong and unless you're using it for a mechanical component where it would have to endure high levels of shear stress at the join it should be fine.