Sometimes “install” refers to installing an app that streams the song for free. In 2021, YouTube Music and Spotify had free tiers (with ads). Simply install the app, search the song, and play. No need to download the MP3 file directly.
In 2021, Google still allowed music purchases. You could buy the song for ₹15-20, download as MP3, and install it on any device. un paarvai alex pandian song download install 2021