There are two airports about one hour drive from Rethymnon city. One airport is in Chania and the other airport is in Heraklion.

You will need to arrange coach transfer. Here are respective websites for public transport https://www.e-ktel.com/en/services/dromologia from Chania and https://www.ktelherlas.gr/en/ from Heraklion

You can pay cash on the coach if the Coach Station is not open. You do not have to book online but check the time table before the flight.