Spotify Family - Link from the invitation Mail is leading to an empty page

[Lioner_]

Hello,

i invited my family to join my family account. So far so good - my brother was able to activate his account. My parents both are using an ipad and when they click on the link in the mail they end up getting sent to an empty spotify page (all white in the middle). As they both don't use a computer they have to use their ipad to get access to the premium account. Anyone any idea why this is not working?