Step 1: Click on "Create call to action" button on your Facebook page.
Step 2: Select the 'Use App' option from the drop down.
Step 3: Switch the button to YES in 'Set up a link to an app' and input the website where you wish to redirect the user when user is not using an iOS or android device
Step 4: Select the ‘App’ option in the 'Choose where to send people on iOS' drop down
Step 5: For iOS, Please use following information:
For eg. If Your app on apple app store is MyAPP, then input the following as