The basic method for installing Sims2Pack files is to use the The Sims? 2: Package Installer that one can download from Aspyr, click on the Link on the Sims 2 Launcher that you get when you are about to play the game. The problem with the Package Installer is that if the Sims2Pack file is a Sim that was created using a Game Engine that is newer than the one used by Bon Voyage that the Installer will tell you that the content is not supported. Usually other Sims2Pack files will work.
There is an Alternative that sometimes works when the Default Installer refuses however the Alternate sometimes fails to work as well. The Alternative is MacUnpac
https://sims.jfade.com/index.php-category=1&subcat=5.html Note that the Alternate needs to have Java Installed and it may not work with the new 64bit Mac OS Catalina or newer.
Regular .package files can be easily installed in the Downloads Folder. The Downloads Folder is located inside The Sims 2 folder in this Path <User>/Library/Containers/com.aspyr.sims2.appstore/Data/Library/Application Support/Aspyr/The Sims 2
I strongly recommend that you put your .package files into subfolders and make sure that they are organized, you will thank me later if you have to look for something.
You may have to unzip or otherwise decode the file if for example you have a .7z file or a .rar file, in that case you use The Unarchiver.app download it if you don't already have it here
https://theunarchiver.comIf you don't find a Downloads folder there you just create a folder inside The Sims 2 folder and name it Downloads.
To go to The Sims 2 folder the easiest way is to type or copy this line ~/Library/Containers/com.aspyr.sims2.appstore/Data/Library/Application Support/Aspyr/The Sims 2
into Go to Folder which is found in the Go menu in the Finder.