No multiplayer on total war?

I downloaded a total war game on steam today to play multiplayer but on the main menu is only allows for a single-player mode. Any way to fix this to allow local, online multiplayer? Thanks.

From this Reddit thread: Mac OS 10.15+ is 64-bit only, and multiplayer is not available.

But, it links to this Steam Community post from Feral, the company that ported it to Mac OS, with the top comment:

Players using a version of OS X before 10.15 can access a compatible version of the game via the Beta tab in the game’s properties window. Select the ‘Mac_Retail_1.1 - macOS 10.14.6 or older only' branch for a version that is compatible with 10.9.5 up to 10.14.6.

So, you could try multiple Mac OS installs to be able to use multiplayer.