To assign an evaluation to a group:
Click the "Customization" button on the lefthand bar
Click the "Evaluation Builder" page
Click on the "Group Assignments" tab at the top
Here you can choose whether every evaluation form is visible for every submission in every group when being reviewed or whether certain evaluation forms appear for certain submissions based on which group they and the reviewer are in.
Select either "Automatically assign all Evaluation forms to all groups" (This will assign every evaluation to every submission in every group) or "I would like to decide the Evaluation forms used for each group" (this will allow you to choose which evaluations are used in which group)
If you select "I would like to decide the Evaluation forms used for each group":
Select "Edit"
Select the checkbox that connects the group to the right form
Select "Save"