The new role system allows you to control all the permissions of your roles from a single details page, which will look like this:
To start migrating, since this is still in beta, you will need to ask someone from the Forest Admin customer success team to switch your project to a "Ready to migrate" status.
Once this is done, go to the Roles tab of your project settings:
Click on Learn more. Then, after you've read the instructions, Start migration process:
This is where it gets interesting:
All your users will be presented in groups (1) that have the exact same permissions (smart action permissions + collection permissions):
If you had created roles and assigned them to smart actions before the migration, they will appear there (2). Additionally, if you had assigned them to users, they will be automatically assigned to those users.
If you wish to create more roles, you can do so by clicking Create a new role (3).
Then assign the available roles to the users of this group (4).
Lastly, review all assigned roles on the last page and validate to finalize the migration process: