The Mythical Marketplace has launched as of 7th of June, 2021. It is currently only open to US, UK & Canadian players only.
In order to access the Mythical Marketplace, you need to be invited to it. Users who were active during Open beta were selected by Mythical Games to register their interest. From that list, users were selected and invited via email for access to the closed Alpha. Invitations shall be sent out in waves.
The marketplace is browser based at the moment and is not accessible in game.
To see the marketplace (Closed Alpha) in action, check out the videos down below from great content creators: