depends where you uploaded the power store files to your site.
if you uploaded them to a subdirectory of the site, you will need to browse to that subdirectory.
for example, if you upload the power store files to the site in a subdirectory named "powerstore", you would start the intallation by browsing to:
or directly to the install directory:
Also, make sure that there is not an installed.txt file in the Connection folder of power store.