RCI Comminuity's Universal stay and play 7 days for price of 2 ($99.95)

[Palenque]

I saw the link on this forum for RCI Community's Universal stay and play pass (7 days for the price of 2) at $99.95 tax included.

Has anyone bought this ticket from them?

Do you have to join RCI? If so how much to join?

What does anyone know about RCI?

Is this legit and do the tickets expire?

This sounds almost too good to be true. There must be a catch.

Any input would be appreciated.