Need to use older version

My computer doesn’t support Rhino 7 so I want to use my 90 day key to use Rhino 6. Am I able to do that?

Sorry, there’s no option for that.
Since V6 is not available for purchase, there’s no sense in an evaluation.

For people that need an additional license, they can purchase a new V7 license, register it, and claim a V6 “Legacy key”, but there is no free 90-day evaluation for older versions of Rhino.