"Add to Cart" button goes to blank page

There is another thread with this same problem, solutions do not help. After clicking Add Product, the next screen displays a blank Page. I had deactivated all plugins and it still does not work. My hosting site is set to PHP 5.2 – I have renamed the original wp online folder and uploaded a new wp online store folder and that did not correct either. Any ideas anyone?

https://www.ads-software.com/plugins/wp-online-store/