Sadly, this avatar does not currently work on Quest. The wingless one could technically be reworked to be Quest-compatible, though. Thank you for the reminder; I will add a wingless Quest variant at some point in an update.
I think it’s over the Quest bone limit…? It’s over various limits on Quest, but the bone limit is the big one. A Quest version would have to have loads of bones deleted, and be rerigged to use the Humanoid bones for its neck and head. It would also lose various functions related to the avatar being a constraint puppet…