Hi,
You should be able to create your organization before setting up the billing, you can verify the prerequisites for creating your organization here:
https://learn.microsoft.com/en-us/azure/devops/organizations/accounts/create-organization?view=azure-devops
Do note that it is recommended to set up billing before making any purchases:
https://learn.microsoft.com/en-us/azure/devops/organizations/billing/set-up-billing-for-your-organization-vs?view=azure-devops
Best regards,
Leon