When you install VE Pro or VE-Ware the plug-in is installed as part of the installation process when Trimble SketchUp is detected on the machine.
If you install SketchUp after installing the VE or you require the latest version of the plug-in you can download it from the link below (requires latest version of VE to be installed).
SketchUp plugin 32-bit: http://www.iesve.com/content/mediaAssets/downloads/2018.0/SketchUpPlugin2018.msi
SketchUp plugin 64-bit: http://www.iesve.com/content/mediaAssets/downloads/2018.0/SketchUpPlugin2018_x64.msi
Note: SketchUp version supported is up to SketchUp 2017 (as of VE 2018)