There may be a few reasons why the Add To Homescreen pop-up message isn't visible.
1. The Add to Homescreen pop-up message only appears the first time the StickyFolio URL is opened on any given device--even if the Folio has not been added to the device's homescreen.
2. Make sure you have the Add to Homescreen pop-up message turned on. To learn how to turn this feature on, read instructions here: Homescreen settings
Troubleshooting tips for iPhone/iPad:
1. Make sure you are not opening the StickyFolio URL in Chrome. Using the Gmail app instead of the iOS device's built-in email program opens the StickyFolio URL in Chrome. Chrome does not support the Add To Home Screen pop-up message function on iOS devices. The Add to Homescreen pop-up message function is reserved for Apple's Safari browser, which is the browser the device's built-in email program uses. If using Gmail, click Chrome's built-in menu (usually three lines in the upper right). Then select Add To Homescreen from the menu.
2. If you are using the iOS device's native email program, check your Safari Settings. Go to Settings>Safari and make sure that cookies are not set to Always Block because this prevents the app from caching.
Here are the recommended settings that allow your app to cache using Safari: