Thank you for your message.
But I did not find anything about installing on a portable drive.
Portable Viewer doesn't require installation. If you already downloaded the Portable Viewer to your drive, then you can start working with it right away.
Portable Viewer stores all files in a single folder that you can copy onto the portable drive.
Here is a related Documentation article that might be helpful: https://www.remoteutilities.com/support/docs/portable-viewer/
Let me know if you have more questions.