If you do not have Snapchat flash, it might be because you do not have an updated version of Snapchat.
Assure your Snapchat app is up-to-date for the highest possibility of receiving the ring light. When an update is ready for the Snapchat app, go to the App Store on your smartphone, and hit the profile symbol in the upper right corner. Then keep scrolling to reload the page, and click "Update" beside the Snapchat app name.