If the “Find Photos Now” button does not respond when you are attempting to upload photos on our Flash-based editor in Apple's Safari web browser, this may be because your browser is in Safe Mode. Safe Mode is a default mode on newer versions of Safari running on Mac’s latest High Sierra operating system.
Adobe has instructions provided on their site for opting certain web domains out of Safe Mode so that all features of Adobe Flash can be run. Please follow the instructions in the following link to allow Picaboo.com to run outside of Safe mode in your browser: https://helpx.adobe.com/flash-player/kb/removing-sandbox-restrictions-your-safari.html
Another option would be to switch to another web browser on your computer. Google Chrome, Mozilla Firefox, and other web browsers do not run into this issue in High Sierra when uploading photos.