Hi, here is a list of some of the more common errors that can result in you not being able to accept the invitation. You may need to decline the invitation and have the group owner send it again. Here is the list in no particular order,
- all iPhones must be iOS 14.6 or higher
- turn off VPN if you use
- log out and in to your Apple ID/iCloud account
- ask Participants and/or Co-owner to log out and into their Apple ID
- make sure you and participants are currently in US.
- make sure Participants and Co-owner has Apple Cash setup in Wallet App on your iPhone
- Family Group members should update their age in Apple ID. >> https://support.apple.com/en-us/HT204164
- Participant must be using same Apple ID they use for Family Sharing Group
- Two factor authentication must be turned on — phone must have password enabled
- Restart iPhone after performing any of the above
- It may be necessary to do a hard restart >> https://support.apple.com/guide/iphone/force-restart-iphone-iph8903c3ee6/ios
It may be necessary to delete the invite and their reinvite to share the Apple Card. I hope this helps.