Why can't I see session tokens in my subscription app?

Hey folks,

I am currently working on subscription app to get session tokens so that our backend API could authenticate the tokens. We have built a simple app by using node js. After I run the command shopify serve and type http://localhost:39351/ in browser, I could navigate the app. But the session token is missing in the app. Another team member is able to see the token on her end. So I am wondering if there is anything I might miss? I seen .env file is created with correct API key, secret etc. Do I need to publish the app to shopify partner in order to get the tokens? I also attach an image of the app below.

Thanks in advance