SQL Compare 16

Backing up a database on a managed instance is not possible when transparent data encryption is enabled. You can disable this using ALTER DATABASE CURRENT SET ENCRYPTION OFF.

Create a shared access signature token for your storage account

Create a SQL Server Credential on your managed instance using the token from the previous step

CREATE CREDENTIAL [https://<mystorageaccountname>.blob.core.windows.net/<mystorageaccountcontainername>] -- this name must match the container path, start with https and must not contain a trailing forward slash.
WITH IDENTITY='SHARED ACCESS SIGNATURE' -- this is a mandatory string, do not change it.
, SECRET = 'sharedaccesssignature' -- this is the shared access signature token and should not include the leading question mark (?).

In the SQL Compare deployment dialog, specify a backup path in the URL text box.