Explanation

Data in SALESDB must encrypted by using Transparent Data Encryption (TDE). The encryption must use your own key.
Step 1: Implement an Azure key vault
You must create an Azure Key Vault and Key to use for TDE
Step 2: Create a key
Step 3: From the settings of the Azure SQL database ...
You turn transparent data encryption on and off on the database level.
References:
https://docs.microsoft.com/en-us/azure/sql-database/transparent-data-encryption-byok-azure-sql-configure