Hi @umilanovich,
Welcome to the Auth0 Community!
I understand that you have some questions regarding Auth0’s Custom Extensions.
Yes, it is still possible to use the “Create Extension”. However, Auth0 Extensions and its Custom Extensions features will eventually be deprecated.
At this time, we will continue to support Auth0 Extensions and Custom Extensions until 2022. That will give you almost two years to continue using Custom Extensions.
By which time, you will need to migrate to something else.
If possible, I would highly recommend using an alternative solution to avoid future overhead and accomplish your needs, such as Terraform or AWS.
Note that we do not expect any replacement strategies to emerge until 2022.
Please let me know if you have any other questions. I would be glad to help.