cant download plugin

I would advise you use FTP to verify the existence of the folder and delete it, then try to download again.

Have you tried searching for the plugin in your wordpress admin via Plugins > Add New > search for ‘wp online store’. It should appear at the top of the list (DO NOT use the Beta version, it is our test store and we do not support it). Follow the install then activate prompts. I have found this to be the least troublesome method for installation.