You will find cabs back to PDC in Akumal, or you can try your luck back on 307 flagging down a collectivo.
That is what we have done countless times with no problems.
But, often in the late afternoon, they are full (of local hotel staff from southern hotels returning to Playa from work most likely
) and you might have to wait 10-15 minutes for a colectivo with room on the highway, but just buy a couple beer from the store by the beach for the wait
- no problemo!