Can't add my kids to family

[cissanlundberg]

Hi, 

I created a family account for my family and sent an invitation to my husband's email. It worked like a charm. Then I sent an invitation to both my son's and my daughter's email and got the same link but then it doesn't work. When I log in for them spotify just want me to add credit card details and doesn't seem to recognise the invitation I sent them. What should I do?