Cannot access cloud shell in Azure AD B2C

I've set up a B2C tenant and want to be able to use either PowerShell or AZ to script. However, when I go to the Azure portal and launch a cloud shell, it says:

"No valid subscriptions found
You need an Azure subscription to use Azure cloud Shell.
Create an Azure subscription"

I do already have a subscription associated with the B2C portal and I thought it's required to complete the portal provisioning. What's missing here? Thanks.