Search for the Smartcode app.
You may get something that looks like the following, in which case tap the icon or title:
If you don't get the above, or once you have tapped, you'll be on a page that looks similar to:
On that page, scroll down until you find this text, and tap Join
Then tap Join:
and the text will change to:
The time this takes seems to be unpredictable. Sometimes it takes a few seconds, sometimes fifteen minutes.
The text doesn't auto update, you will need to tap back and come back into the app's detail page every minute or two.
Once you are entered, the text will become:
And the Open button at the top will become Update letting you update to the Smartcode (beta) version of the app.