As far as we have been able to find out, the Isle of Rhodes has one airport. This airport is placed not far from the conference site (around 10 km), meaning that it may be adequate to use taxi between the airport and the hotel. Most, if not all, air connections require that you change plane in Athens.
Alternatively, you may take a ferry from Piraeus to Rhodes. It is a long tour (about 18 h) and brings you to the town of Rhodes, which is the main town on the island. From here it is about 10 km to the hotel.

The following two links are the official links of the hotel.