To get the Project Link, select your SysMLv2 project from the Teamwork Cloud resources page.
From the Project, select the 3 vertical points to the right of the project, then select Get project link.

Copy the link displayed, and paste it to the Project Link text field.
Once the association is created, you can publish your design.
Optional parameters
The design's name can later be edited from the design details page.
The target folder can later be modified from the Designs Tree administration.