iClone Indigo Render Plug-in 1.53.4711.1 could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. We recommend checking the downloaded files with any free antivirus. The most popular version of the iClone Indigo Render Plug-in 1.2. The software belongs to Photo & Graphics Tools. The actual developer of the software is Reallusion Inc.
From the developer:
Indigo Render Plug-in for iClone lest you utilize GPU accelerated raytracing render capabilities in Indigo RT. This addon provides automatic shader mapping between iClone and Indigo; a simple one-click render will automatically convert shader information and provide accurate shader interpretation to your final render.
You may want to check out more software, such as iClone, iClone 3DXchange or iClone 3DXchange Trial, which might be related to iClone Indigo Render Plug-in.