Are managers and collaborators paying users?

Yes

Paid subscriptions are the admin, manager and collaborator in your environment.

You can manage all active licences from your settings in the "Accounts" tab.

It is useful to add admin, manager or collaborator users to your environment when you want them to be able to create projects, validate tasks, modify a report, etc. on their own.

TIPS : External users (customers, contractors, etc.) are completely free, regardless of their number.