As part of the pairing process for the mobile apps, you will need to copy the image from the micro:bit screen into the app.
To do this, tap on the highest LED in each column. In this example, the whole column is lit, so tap on the top LED to light up the whole column.
Repeat the process for each column.
If you make a mistake, just tap on the lowest LED in the column to reset it. The lowest LED is always lit in a micro:bit pairing pattern, so you will not be able to turn it off.
Attribution: finger touch icon by Hea Poh Lin from the Noun Project