You have two options:
Game File Transfer over Local Network
The first one is to use Steam's "Game File Transfer over Local Network". This allows you to share a game between computers in the same network.
Some well made games like Euro Truck Simulator 2 use the same files for all operating systems it supports, and the only thing different are the executables. In the case of games like this, it's the best option, as you don't need to do anything other than download the game.
You just enable the option in the Steam Settings and the other PCs in the network will automatically pull the game files from your Mac, and then get the Windows executables from Steam, which for good games should not be more than a couple of megabytes.
![enter image description here](https://cdn.statically.io/img/i.sstatic.net/Gu2ZS.png)
Manual Download with DepotDownloader
You can use DepotDownloader to download a specific game version for a specific operating system.
To download a specific game with DepotDownloader, follow this set of steps:
- Download and Install .NET for macOS, either .NET 6 or .NET 7
- Download DepotDownloader (click on the ZIP file)
- Extract said ZIP File somewhere
- Remove the file called DepotDownloader.runtimeconfig.json
- Open a new Terminal window from Finder
- Enter
dotnet DepotDownloader.dll -app <APPID> -os windows -username <USERNAME> -password <PASSWORD>
(replace USERNAME and PASSWORD with your login details, and APPID with the Game's specific appid) and press enter
Then, you just wait for DepotDownloader to download the entirety of the Windows version of that specific game.
To install those files, you start the download of the game in the other PC, close Steam and then replace the game files with the folder created by DepotDownloader. Steam will then verify that all of the files are present and that nothing needs to be downloaded.