Can't add a family member to family sharing

We've invited my daughter to join Family Sharing. She got an email regarding our invite, but when she clicks the button, she is taken to iCloud with no further instructions. When she goes to Family Sharing in her settings, it asks her what she wants to share with her family, as if she's setting up family sharing for her family. We've resent the invitation a couple of times, and tried to add her directly using her Apple ID. It says that we invited her already and she must accept the invitation. Anyone have any idea how to make this work? Thanks in advance.