Add new repository SQL error


I've got a new instance of 5.9.2 installed and I'm trying to add a repository, when I click save I get the following error:

A database error occurred. The error was: message: [Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Login failed for user ''., sqlstate: 28000, code: 18456, var_info: -Could not create the MetaStore repository.

In ControlPoint MetaStore.cfg I have the following: 

ConnectionString=Driver={ODBC Driver 17 for SQL Server};Server=sql;Initial Catalog=ControlPointMetaStore;Integrated Security=SSPI;

The MetaStore service is running as the user who has full access to the ControlPointMetaStore database - do I need to do something else to get the credentials to work?