We don't support preview print on Safari & Firefox.
In other words, you won't see any printer icon on the previewer.
On Safari & Firefox, the alternative way is to download PDF and print.
Step-by-Step
Move the mouse to Generate Labels button and click Download on the product/address label page.
Open the PDF file by Firefox. Click the Print icon.
3. Click the Print using the system dialog at the bottom as the above image.
4. Click Preferences.
5. Select the correct Paper Size that you are using. Click OK.
7. Orientation can be different on different devices.
8. Click OK, and print.