Download a Telugu Keyboard: Use a highly-rated app like Desh Telugu Keyboard or the standard Gboard. Enable the Keyboard: Open your phone's Settings. Go to System > Languages & input > On-screen keyboard.
Option 2: Error / status message (if installation fails)
Malware: Unlike the Play Store, these sites don't always vet the files they host.
Educational Resources: Features for learning the Telugu script, including writing practice (vowels, consonants, and guninthalu) and vocabulary building.
Playback test
"Nuvvu Telugu vaadithe – nuvve Telugu Six. Nuvvu icche gnaname – aa 4 Ru."
(If you speak Telugu – you are the Telugu Six. The knowledge you give – that is the 4 Ru.)