Hello! I’m finishing the project on my Mac laptop and I’m lost. I'm new for this ... Dont understand how to select all legs.. what key do I press for Mac? Control key doesn’t select all of them

I'm done but my table is floating lol 😆 how can I lower it in the model group? (the course Fast Start in SketchUp)

Is there another file type I can use when exporting my scene? My computer is having problems exporting I just keep getting the loading screen for a long time