For each one of your course collections at least one LTI group will automatically be created in the Groups pane of your MediaCore site. The group will appear with the name of your course collection. You'll notice that some LTI collections have multiple groups created for them, this is because you have users with different roles logged into this collection.
In the screenshot below you'll notice that there are 2 collections for "Applied Finance Project" - one for the instructor role and one for the learner role. Each user that has viewed this course with a particular role will automatically be added to the appropriate group. You can see the number of users in each group next to the group name.
To access the "Groups" page in MediaCore navigate to "Site Settings" and click on "Groups". To change the role associated with a group click on the dropdown menu next to the group name and choose a new role.
Alternatively, you can navigate to Admin Panel "Library" > select the collection this group belongs to > click on the cog next to the collection and select "Permissions". From here, click on the dropdown menu next to the role and select a new role.
You can edit the permissions associated with each one of your LTI Roles by navigating to Site Settings > Roles > Click "Edit" next to the Role you'd like to update > Select the permissions you'd like that Role to have and click "Save".
The role from your LMS will map to the closest LTI role listed on this page: