Hello @StefanoL ,
It seems like you are stuck at the very beginning of the tutorial where they say :
If you press "Generate Code" or "Run Simulator" the specified virtual functions will be generated by the Designer. Let us start by integrating the four functions for the arrow buttons. To keep track of the values for hour and minute, two counters are also added.
Now add the following code:
The issue there is that you added a wildcard but did not specify the characters this wildcard can take.
You need to specify which characters can take by going into "Texts", "Typographies" and than filling the fields "Wildcard ranges" for example :

In this case my wildcard could take all the ASCII values.
In your case you just need numbers do you could either type "0,1,2,3,4,5,6,7,8,9" or "0x30-0x39".
As @Andrew Neil mentioned, you seems to be quite new to TouchGFX so you should start simple.
Have you done the previous tutorials ? (tuto 1 and tuto 2)
You can also find resources here : UI development
Hope this helps.
Don’t hesitate to give us a feedback or give more precisions and tell us if the issue is solved! :smiling_face_with_smiling_eyes: