Traveling on the Rinkai Line Question

Hi,
I am traveling from Ikebukuro station to Tokyo Teleport station and I am aware that from Osaki to Tokyo Teleport station it isn't covered by the JR Rail pass. I am wondering how do I pay for the ticket between Osaki and Tokyo Teleport station. Do I get off at Osaki and pay for it there or can I pay for the ticket at the end of my trip at Tokyo Teleport station and how would I go about doing that.
Kind Regards Caitie