What Mario told you will help see what is available, not just on web apps but to access a custom field, because it has a name that can be spaces etc you need to do it like the follow:
{{this.['My Custom Field']}} is how you get a custom fields data.
What Mario told you will help see what is available, not just on web apps but to access a custom field, because it has a name that can be spaces etc you need to do it like the follow:
{{this.['My Custom Field']}} is how you get a custom fields data.