This is the documentation MIT has provided so far Oluwakemi Gallery Introduction
Logging in and Using the New Gallery
Because the existing Gallery is integrated into MIT App Inventor there was no need for a separate login. Because the new gallery is separate than MIT App Inventor you need to login into it. However, you do not use a separate login. Instead, from the Projects Tab in MIT App Inventor there is a new button “Login to Gallery” that opens the Gallery in a new window and logs you in.
You publish an app in the new gallery by selecting it in the Projects Tab in MIT App Inventor and press the “Publish to Gallery” button. If you are not already logged into the gallery, you will be automatically logged in.