Is it meant to be a public app using personal JWT? In other words, do you expect any RingCentral customers can use your app if if they provide you their JWT token?

Yes. This is for public use in marketplace so any RC customer can add this to their account.

Also checking how can I guide RC customers to find their JWT token. Please guide me with some steps. Do they have to have a developer account also.

Also how will RC users without developer account can access our application.

That is the current limitation of using JWT token for public app. So currently, your app users requirement must be RingCentral customers with an Ultimate or Enterprise plan.

But soon all RingCentral customers will have access to developer platform.