Invited to collaborate but no files or folder showing

I use Box through my work to view media files.  A colleague from an external organisation has sent me an invitation to collaborate on a folder.  I’ve received an email with a link but when I click the link it wants me to sign up to a new box account. If I sign into my existing account via the link there is no folder showing, there are no pending invitations and in fact I cannot even see any reference to shared files anywhere. This is an extremely time sensitive matter (as in needs resolved now) required for court proceedings.