See
https://www.dittomusic.com/sell-your-music/google-play (or do a search for similar options). But remember, anyone can download it, not just your employees.
If you want just your employees to be able to download it, just run a website on your company server if you have one (see
xampp if you don't already have one running on at least one computer in your office), put the song file on the server and post a link on the server to the song file. Then they can connect to the server and download the song (and no one not connected to the company network can).