ReasonTalk.com

We currently create meditation tracks, around 20-30 minutes each. Our customer wants to sell them to his clients but got no idea were to host it. Does anyone have an idea were to start?

PS: we could use LANDR or something to publish the tracks on itunes etc, BUT we do not want this. It is an offer especially for some clients, not or the masses.

Any platform (In your case there is no platform not to touch)

You could simply rent some webspace at a hosting provider. Also some transfer services like wetransfer, goodle drive, or mega might work (depending on your need for long term availability of your download links).

once you've sold $20's worth of tracks on https://bandcamp.com/ you can upload tracks upto 600Mb in size. Till then the limit is still a rather generous 291Mb.
Probably worth giving a friend $20 to buy some of your music with to increase your limit if it's an issue.