It was some sort of collaborative platform for people working on projects or something like that

Please tell me someone remembers Google wave and the insane amount people were paying on eBay for an invitation. (Sorry, just randomly remember it when I saw Google+)

I do use their app but I’m pretty sure you can have your own RSS for audiobooks, and I’m assuming for podcasts too. I really recommend you give it a go :) let me know if you need any help, or just at the selfhosted community. Happy to help

Edit: just checked, yes you can have your own RSS with audiobookshelf, so you can still serve to your favorite podcast app.

If self hosting is your thing I use audiobookshelf to download the podcasts I subscribe too, has a nice interface to navigate them, and even mobile apps.

Not quite what you’re looking for (public archive) but a good starting point for a personal archive