Install Octane Render™ Plugin for Cinema 4D®:

Step 1:  Log in to your Otoy account and navigate to "Downloads" section. From here you can download the latest edition of the Plugin (see the image below). You can also get the latest edition of Plugin from here

Step 2:  After downloading the archive file, extract the content to your Cinema 4D/Plugins directory (see the image below).

Step 3:  In c4doctane folder you will see different versions of the Plugin. Keep the correct version and remove the others.

Make sure that Cinema 4D is not running in the background.