I found this, and it worked for me:
CREATE LOGIN BackupRestoreAdmin WITH PASSWORD='$tr0ngP@$$w0rd'
GO
CREATE USER BackupRestoreAdmin FOR LOGIN BackupRestoreAdmin
GO
EXEC sp_addsrvrolemember 'BackupRestoreAdmin', 'dbcreator'
GO
EXEC sp_addrolemember 'db_owner','BackupRestoreAdmin'
GO