take the Bus from bayahibe to Higuey, they drop You off at the Parada/Station for the Punta Cana Busses.
here You have the choice between 3 Lines
* Cabeza de Toro
* Bavaro
* Punta Cana
the Punta Cana Line will drop You off at the entrance of the Punta Cana Airport, they depart from Higuey all day long every 30 minutes.
no Spanish needed at all to use those Guagua Services, in bayahibe you just have to ask about Higuey to sit on the Right Bus, and at the Terminal in Higuey You tell the Staff "Punta Cana Airport", they will point you out which one of the 3 is Yours.
when arriving in Higuey on the Bus from Bayahibe you let the Driver know you want to go to "Punta Cana", so they drop you off at the appropriate station.
they are used to such travellers, nothing out of the ordinary.
have Fun
Mike