Since the Cloud Service is a Classic resource that is not directly compatible with the Azure Resource Manager model, you can't associate it with the Azure Resource Manager Storage accounts. Here are few options:
Deploying through REST API.
When you deploy through Service Management REST API, you could get around the limitation by specifying a SAS URL to the blob storage, which will work with both Classic and Azure Resource Manager Storage account. Read more about the 'PackageUrl' property here.
Deploying through Azure portal.
This will work from the Azure portal as the call goes through a proxy/shim that allows communication between Azure Resource Manager and Classic resources.
Source: Azure Documentation FAQ