Most of it can be referenced in this article
files:
Steam application Steam.app
Steam that participated in Family Beta (2 in 1 has been packaged into dmg)
Detailed instructions: After extracting the Steam application, place it in the Applications folder.
For the App Bundle, go to the folder in Finder
~/Library/Application Support/Steam/
If the folder does not exist, open Steam once to generate the folder or cd to Application Support to create a Steam folder.
Extract the Steam.AppBundle package and then copy the Steam.AppBundle folder to the Steam folder mentioned above, and you are done.
For those who downloaded the Family Test package, after completing step 1 above, please check the Steam inside the package (one is the App Bundle and the other is the Steam application).
To distinguish them, click on them and then right-click or click the small gear in the Finder window. If the menu shows an option called Show Package Contents, then the selected one is Steam.app.
Manually create a folder called Steam.AppBundle in the Steam folder, then place the Steam icon file that is not the Steam application into the Steam.AppBundle folder, and you are done.
QA: What to do if Steam sometimes does not display the window?
Force quit directly (usually only occurs in the FB version of Steam).