Hi @jakeriley,
Welcome to the Auth0 Community!
If you enabled the custom domains for your terraform plan being on a Free plan, yes, you should get a 402 error.
This is due to the new changes. With the latest pricing changes introduced, “custom domains” is available for a free subscription with some conditions.
Note that the current free plan restricts access to custom domain configuration in a free subscription based on credit card verification. This means that for a free subscription tenant admin to be able to configure custom text, they must first complete the credit card verification step.
The credit card verification step will NOT imply actual charges, so there will be no costs associated with configuring or using the custom domain.
I recommend checking this article for more information on custom domains: Using Custom Domains with Free Tenants
Please note that the Auth0 terraform provider supports the Custom Domain for the management API. However, while initializing the provider, you need to pass the audience parameter set to your canonical domain.
I assume your tenant is in the US-3 region, so your tenant’s canonical domain is a sub-domain of us.auth0.com.
Please let me know if this clarifies for you!
Thanks,
Timotei