Fill the details, set the Redirect URL and Save changes
If HOMEPAGE is the url of the homepage of your website save exactly the following url
If using Super Socializer plugin, save HOMEPAGE/SuperSocializerAuth/Foursquare If using Heateor Social Login plugin, save HOMEPAGE/HeateorSlAuth/Foursquare
For example, if your website is https://yourwebsite.com, you need to save https://yourwebsite.com/SuperSocializerAuth/Foursquare or https://yourwebsite.com/HeateorSlAuth/Foursquare in this option
After creating the App, you will be taken to a screen where you can copy Foursquare Client ID and Secret.