IPTV Smarters Pro is popular because the login flow is familiar and the layout is manageable for beginners. It can work well when your provider supports the right account format.
What to check first
Enter server, username and password details exactly as supplied. Extra spaces, old credentials or the wrong login type can stop the app from loading.
Practical Firestick advice
If EPG or categories do not appear, refresh the app data, check the subscription status and confirm that the service supplies guide information.
Use IPTV apps and playlists only with sources you are authorised to access. A player app does not provide channels by itself.