I don’t think ‘you’ need to worry about this. Only proof of where you are staying. Copied this …. You do not need to submit a TM30 for yourself. Instead, this must be completed within 24 hours of your arrival by the owners of the lodging where you are staying. A fine of 800THB, increasing to 1600THB/person for the property owner, can be imposed for failure to accomplish this.
Depends on where you are from. I am British. Visited Phu Quoc in January and mainland last week. No visa required. If you are American you will require as they want to check you are not trying to invade 😂