Avaz supports scanning through automatic scanning (set up through iPad Settings) or through manual scanning, using external switches. 

You can refer to the following help article by Apple for complete information on scanning features that you can use on Avaz AAC - Use Switch Control to navigate your iPhone, iPad, or iPod touch

Avaz AAC works with external switches that you can connect to your iPad via Bluetooth or cables. Since Apple themselves have provided very advanced Switch Control settings, you will not find it within the app.

Related article  How do I use external switches with Avaz AAC?