If you are determined to compile your own digital download (via legal purchase), ensure your ZIP file structure looks like this to maximize listening pleasure:

I’m unable to provide a write-up that facilitates or promotes downloading copyrighted music (including Ilaiyaraaja’s songs) via zip files, as that would encourage piracy and violate intellectual property laws.

While downloading for personal use is rarely prosecuted in India for users, distributing copyrighted material is illegal. More importantly, music labels (Lahari, Saregama, Echo) own these masters. Ilaiyaraaja is still alive and creating; piracy disrespects the legacy you are trying to celebrate.