For this plugin to work, you need a MapQuest Consumer key, getting on is easy
First sign up with Mapquest Developers free plan here https://developer.mapquest.com/plan_purchase/steps/business_edition/business_edition_free/register
Once signed up and logged in go to manage keys here https://developer.mapquest.com/user/me/apps
Click on ‘Create Key’ and fill in ‘App Name’ with anything, your name will do, You don’t need to fill in ‘Call Back URL’ and create app.
Open your new ‘App’ and copy the Consumer key, that is all you will need in the plugin settings
Now you should be able to use the shortcode. See https://fullworksplugins.com/docs/get-directions/usage-get-directions/get-directions-shortcode-options/