The installation follows the sketchup standards, the downloaded file is an *.rbz file, which can be installed from the sketchup extensions menu.
When you want to download a test version,
please go to
www.AREAL3D.eu and order it
(you will have to enter your email adress and optionally (hopefully) your name).
You will automatically get an email with a download link for AREAL3D.
The installed files remain unchanged, if you buy a license, so no further installation, besides installing the license, is required.