PowerStore is not an Extension, it is a Solution Pack.
A Solution Pack is a set of pre built pages that add functionality to your site.
To configure PowerStore, you need to extract the downloaded PHP files to your site. Create the database that is included in the downloaded files. Modify the Connection file to connect to the MySQL database and modify the WA_Globals File.
All of these instructions are included in read_me.htm file that is included in the downloaded files or the getting starteed guide that is linked on the PowerStore Support page: