On the left side of the website if you click on Android it should take you to the download page. The dev did say it'd remain up for a few weeks if not months though. Direct link: http://fildo.net/android
You can also reach the github repo through the dev's history - /u/AdminFildo, or here: https://github.com/SergioZgz/Fildo
Try fildo.net I was working on it for a lot of years (check fildo.es whois :) ) but I take it seriously only hast 15 months...
Try it and just tell me what do you need :) I'm improving it every week :)
You could search stream listen download, search for an artist or album and share with friends. You could import your spotify playlist too.
Enjoy it :)
BTW is legal, is just a search engine to third party sites... like VK or NetEase.