The second option is to download the RBZ file which does not require administrator rights but is installed from within the Sketchup’s Extension Manager. It is an executable which requires administrator rights that will install the Standalone version of Raylectron and also gives you a selection of all versions of Sketchup installed where you can select for which version of Sketchup you which to install Raylectron for.
The first and recommended way is to use the Self Installer. There are two ways to install Raylectron…