When you update to Safari version 10.0 or higher, flash player is disabled by default. To re-enable flash for this browser follow the below instructions:
1. Open Safari, and choose Safari > Preferences.
Note: If you are viewing Safari in full-screen mode, mouse over the top of the browser screen to see the menu.
3. Select Adobe Flash Player from left of the plug in window
4. From the When visiting other websites menu, choose On, and then click Done.
5. If you have any websites appearing in Currently Open Websites area, choose On in the menu on the right.
Once this is complete, all flash based sites and extensions should be viewable on your Safari browser.