Provider — it’s an external panel service that you use for your panel’s services. Also, you can create as a provider your own service source.
As for default, while you import new services from the external panel, services are with a similar description and the same smm service provider imported to you as on the external panel. However, you can change the provider for any of the services or set several for one service at once. In this case, the order will be created on the provider that offers the best price at the moment.