CA Test Data Manager (TDM) requires a compound license for Datamaker and all other components, including Fast Data Masker (FDM). You will be applying the same key you received for TDM, also known as Datamaker, for FDM’s license activation.
If you do not already have a TDM or FDM license, you can request one using a Customer Care Case Request form: https://catech.force.com/customer/CustomerCareForm
When the request is processed, you will receive an activation key by email in the form of a text file. The key should be one long line of alphanumeric characters.