Hello @abdullah nashat
This is happening because you havent been assigned a directory permission and the Global Administrator in the tenant has disabled the permission to allow users create an application within the tenant. Also, the Administrator has enabled the feature to prevent users from accessing the Entra ID which is the reason for the issue you are experiencing with the Entra ID
Having an Owner role on the subscription doesnt give you the permission to manage Entra ID objects (like users, applications, groups). Entra ID permissions are different from Subscription permissions.
You need to contact your Organization (tenant) Administrator to assist with an Application Administrator role to be able to Register an application.
Let me know if further assistance is required.
Please accept the answer if it helps.