The providerID, is retrieved from this endpoint 

https://api.sandbox.mobilepay.dk/subscriptions/api/merchants/me

existing in “Subscriptions Integrator” product. It will give you all providers existing under that “access token”.

• You will get configuration details: payment_status_callback_url, scheme, key, password, scope.
• Providers represents your customers (which is a MobilePay Merchant) providerId represents a particular subscription provider (for example, if a single merchant has several brands, each brand would be a subscription provider). Currently, a merchant grants you permissions to all their subscription providers, so once you get an access token, first thing you need to do is call GET /api/merchants/me which will return you a list of subscription providers for that merchant, with their IDs and basic information