Depending on the option you presently have set, Gatekeeper will give a warning that the file is either “not from the Mac App Store” - not from the Mac App Store or from an Identified Developer or it will simply run normally. You can change the choice in the Gatekeeper menu as seen above to “Anywhere” or you can simply right click the mouse and opt to run the PTE file. You may also CTRL Click the mouse and opt to run the file. At present, there is no other solution because obviously everyone isn't going to pay for your slideshows through the Mac Store and Wnsoft is not yet an “Identified Developer” … which is actually a category for application software developers rather than for the MacIntosh output of a program used by thousands of people. Perhaps when a MacIntosh version of PTE is released, this will be resolved but for now this is the solution…