Attending the State of the Map 2021 is free, but in order to participate in the interactive conference platform on venueless, you need to register yourself and get your personal ticket. The digital ticket will be emailed to you immediately and contains the link to the SotM 2021 online event.
In case you already got a ticket, but can't attend anymore, please let us know via a short email to sotm@openstreetmap.org, so we can open the slot for other attendees. Thank you very much!
If the above form doesn't work for you, you can also try this alternative link of the booking page.