As you can imagine the ramp is very LONG. My wife uses a manual wheelchair and took a break on the second landing for a second, but managed it herself without much issue.
There are not a lot of videos or pictures of the accessible Treehouses that I have ever seen.
AllEars.net has some, but they are from 2009. The decor has been updated, but the general footprint should be the same. Treehouse Video entrance ramp
Treehouse Video main bedroom