Question about "Open" button on the "About" of Teams Android mobile

Dear Sir

Unlike iOS mobile, I found "About" tab on Teams Android mobile.

I works well. However, there is an "Open" button at the bottom side.

I'm still developing my Teams app. So I'm testing the app by locally upload.

The "Open" button of My app is not activated. 

Other app installed from Teams Store has the button activated below.

Do I have to set/configure to activate this "Open" button on the About?

Otherwise, is it related to Teams Store production. 

Many thanks

BH