It supports Linux vs Mac, but neither can play with Windows as they gave details on in this post.

If you are installing Tales of Valor from the disc, you do not need this patch because its contained on the disc.

Shame they were never able to get full cross-platform online play sorted. Its size is due to the patch containing assets of the Tales of Valor expansion so the base game and Opposing Fronts can be compatible with it, as well as reward units and Operation modes. Nice to see Feral are keeping up with their older ports. That big June update includes five new Commanders free for everyone, created in partnership with the CoH2 community. Recently, the Linux version fell behind in patches by a few months but no more! While there's quite a lot of updates to the balance of the game, there's also the rather huge Commander Update from June that we now have.

Originally released by Relic Entertainment and SEGA back in 2013, they teamed up with Feral Interactive to provide a Linux port in 2015. Feral Interactive, the company that ported the RTS game Company of Heroes 2 to Linux just today pushed a big upgrade the bring the Linux version up to date with all the recent patches to the Windows version.

Company of heroes 2 patch 2019