Remember to accept the IRI invitation on the IRI website. THis is needed by June 4.
After you accept, you should receive a paypal invoice.
These are sent "manually", but you should get one within 24 hours (maybe a little longer on a holiday weekend

).
If you do not get an invoice, please PM me and let me know. A few have not gone through, but have been OK on the second try.
Also, the invoice will be sent to the primary contact name provided on the acceptance. Be sure that is who you want it to go to.