Check their "Contests" page regularly. You can download the full stem packs for free during the entry period.
If your primary goal is finding vocals, Voclr is arguably the best specialized site out there. It features a clean interface and a robust search engine to help you find acapellas by BPM and key. remixpacksclub alternative free
Looperman is a community-driven powerhouse. While it focuses heavily on loops and samples, the "Acapellas" section is legendary. Everything uploaded here is shared by the creators themselves. Check their "Contests" page regularly