The plugin does not require OctaneRender™ Standalone Edition to be installed. However you must own a license for Standalone Edition in order to use the plugin (your Standalone credentials will be requested when you activate the plugin). If you do install Standalone Edition, it does not need to be the same Octane version as the plugin since they operate separately.
The plugin requires:
It runs under Windows 64-bit or Macintosh OS X.
It is also highly recommended that you use your on-board graphics or a second graphics card for the Windows display adapter. If you do not have an onboard or second graphics card, use the Low Priority Render Priority.
If you are running a GTX 690, or multiple graphics cards, it is important to disable SLI in the Nvidia control panel.