If you are planning on taking a ferry, there might be another requirement for paperwork. It was unclear on Greek gov site, so I contacted the ferry company..Kamelialines, they sent me another form to complete. No instructions, though on what to do with it when complete. I’m going from Corfu to Paxos and back precruise.
Probably would be wise to contact the ferry company you are traveling with just in case
good news was I got my code and plf within 5 minutes in filing the form
only 5 more days before I start my European journey with an eventual cruise of Ovation starting August 14.