Hi @bhavesh , welcome to the forum…

9 out of 10 times, folks, including myself, forget to send the CCG or JWT application to authorization, which might explain your situation.

In the developer console for your application, locate the Authorization tab and click the review and submit button. It looks like this:

Once you’ve done that, the administrator needs to approve the application. In the admin console, navigate to apps, and locate the custom apps amanager. From there authorize the application. Looks something like this:

At first glance and with the information you provided, this should do it.

Let us know.

Best regards

Rui