In order to elicit a postalcode from the user, you could use for instance the Ask: open or Ask: number nodes, depending on the format of your postalcode. However, if you really want a valid postalcode check, this skill helps you do just that by introducing a node to your Flow designer that will ask a postalcode and check the validity.
Installing the Zipcode flows skill
Go to packages
Click on Browse skills
Click on the corresponding tile
Click install
Find the zipcode flows skill
Install the skill
Use the Ask Zipcode node
Now you can go to your flow canvas and start using the Ask zipcode node.
