Credits can only be shared if the license itself is shared (i.e. same email address and license key used to activate).
If you add seats for your license (this can be done at the PlaceMaker portal), any credits that you purchase will be assigned to that license and go into a shared credits pool that all users of that license will have access to.
By logging into the PlaceMaker portal, you can track the usage of credits for your team.
If you want to combine your team's existing separate licenses into a shared team license, please submit a support request.