In step 6, we attach the textField to the query string in the URL but the code is looking for the textField/title in the response body as show in line 74.
The fix would simply put { "title":"{{TextField}}" }
in the web request body or put the appropriate key-value depending on the webhook
In "Step 6 - Complete Webhook Action Fields", the image indicated the web request to be GET. But route accepts only POST. Editting the image may be annoying so adding a little note may be enough instead.