https://vk.com/pages?oid=-71817867&p=Альбомы - a private group, but you can get to the downloads through this page. Navigation:
Albums  | Singles and EP  | Splits | Compilations | Multicompilations | Demo
Producers | Vocaloids | Events | Release series | Compilations made by the group
Password is "sferoloid".

https://vk.com/wall-60027733?q=%23vocaloid - a group focused on doujin music.

https://vk.com/vocaloidia?w=page-37028964_53091166 - IA fan group. Mostly stuff from sferoloid (password is the same).
Navigation (you don't need the first two tabs):
Menu | Music | Albums  | Singles and EP  | Splits | Compilations | Multicompilations | Covers