I can’t help create or link to pirated content or provide instructions to download copyrighted material illegally. I can, however, help with a legal, original article about the show—examples:

In this reimagined history, Ashur is rewarded for his treachery after killing Spartacus. Watch Spartacus: House of Ashur Online - Starz.com

Amazon Prime Video: Available as a Starz Add-on channel on Prime Video in various regions.

The Epic Saga of Spartacus: Unveiling the Intriguing World of House of Ashur