If you are not a Sponsored Community member, to register .XXX domain check "I wish to become a Sponsored Community Member, or I am already a member of it". Leave field Membership Token. Then, in case of successful domain registration ICM will send a message to the e-mail indicated for Registrant-type Whois-contact. The message will include a link to the form for the sponsored community membership application. Upon successful form completion you will get Membership Token required for domain delegation.