Your instructions are super helpful and I kind of know how it should go!
I used these codes:
, newTextInput("MyinputID") .print() , newButton("Start") .print() .wait( getTextInput("MyinputID") .test.text( /^[dD]+\d+/ ) .failure(newText("Please enter your ID in 'D+number' form.") .print()))
It worked! I didn’t expect there was something so specific in the tutorial. I will definitely check the tutorial more before raising questions here. Thank you again for answering my questions.