Use of sandbox

Rolf-42  I have a paid subscription - But microsoft learning "Check your work" is only able to verify the concierges subscription  - For example - have a look at this learning module - https://docs.microsoft.com/en-us/learn/modules/create-cosmos-db-for-scale/2-create-an-account . I am doing a Microsoft challenge learning and need to use the Learning Portal also sandboxes created using concierges subscription 

Additionally I have another issue after getting more sandboxes on the specific  learning program uses cosmos - I get the following issue when creating database . Any way to resolve this ?

{"code":"DeploymentFailed","message":"At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/DeployOperations for usage details.","details":[{"code":"BadRequest","message":"{\r\n \"code\": \"BadRequest\",\r\n \"message\": \"Free tier has already been applied to another Azure Cosmos DB account in this subscription. To apply free tier to this account, you can select another subscription for this account or delete the existing free tier account. You can have up to one free tier account per subscription.\\r\\nActivityId: 9149a466-1a53-4a84-8743-89caeee91fd2, Microsoft.Azure.Documents.Common/2.11.0\"\r\n}"}]}

concierges subscription