There are three ways to scan a Nametag in real-time.
Method 1: From the Story Screen
This is the easiest way to scan an Instagram Nametag. You need to go to the Story screen by swiping right on the home screen of the Instagram app. You can also tap on the Camera icon at the top-left corner.

Once in the camera mode, point your camera towards the Nametag and long press on your screen. Instagram will scan the Nametag automatically and will recognize the user to give you two options — Follow or View profile. Select either of them.

Method 2: From Search
Another option to scan is possible from the Search or Explore feed. When you open the Search tab, you will find a small scan icon on the right side of the Search bar. Tap on it, and you will see the scan screen. Again, point your camera towards the Nametag and hold the screen until your phone recognizes the profile.

You can access your Nametag from the Search screen as well. When you are in the scan mode, you will find Go to your Nametag option at the bottom. Tap on it.

Method 3: From Profile Screen
When you access your Nametag from the profile screen, you can also scan Nametags from the same screen.
To do so, tap on the Scan a Nametag option present at the bottom.