This is a common error which we can see when we setup a new azure account. Sometime this is not an error and this error is coming because of a mistake that we are doing.
If you experience this issue you an start with the below steps to troubleshoot this.
First, you need to check whether you have logged into the correct account. Because mainly there two categories, and if you are in the wrong account, then you will not be able to see your subscription.
This option will prompt once you type your user name and if you have personal and work accounts created for the same email address.
If this is not the case, then you can check the User permission under the Microsoft Azure Access control (IAM).
Check the Role that is assigned for the email address that you are using and you have to have minimum owner permission to access your subscription.
If that is not set. Give the owner's permission.
Then login into your Azure portal by using that email account. Now you should be able to see the subscriptions.