I feel like I'm asking a really stupid question, but here goes - I can't find any sort of frequent flyer club for Fiji Airways that's free. The Tabua Club I saw on their website costs!! And evidently if I'm flying on just a FJ flight number I can't accumulate miles with AA (at least)?

What am I missing here? How can I use FJ flights, with FJ flight numbers (e.g. NAN to VAV) to earn miles/credit, other than the obvious Chase Sapphire Reserve points? TIA