To get LayOut you need SketchUp Pro. Contact SketchUp Sales and see if they’ll sell you a license for SU2016 Pro. They might since you can’t use SU2017 on your computer. They might not, though. Normally, you can only buy a license for the current version. Only the sales department can tell you if they’d sell you a license for SU2016.
If I upgrade my computer, will my 2016 SU files transfer to 2017 so that I can put the 3D dwgs into 2017 Layout without any problems? I don’t want my 2016 SU 3D dwg to go to waste if I upgrade.