Splatoon 2 is a Nintendo Switch exclusive, and there is no official version for PC. Any site claiming to offer a "Splatoon 2 PC Free Download" is likely a scam or distributing malware.

You arrive as a fresh Inkling, ready for Turf War, but you are quickly intercepted by Marie, one-half of the famous Squid Sisters. She reveals a dire secret: her partner, Callie, has gone missing along with the Great Zapfish. She recruits you as of the New Squidbeak Splatoon. Into the Octarian Depths

Recover mini-Zapfish held captive in bizarre, floating obstacle courses.