[Affinity Designer cannot save due to Windows 10 security blocking unauthorized change.]

I'm using the trial version of Affinity Designer and when I try to save a project file to a folder, it says I can't ("the file cannot be found") and Windows 10's security blocks the unauthorized change. There is no option to authorize the changes when I try to and, since it's a Windows app, I can't access the program files to manually add it to the exceptions list.