On a laptop or desktop device:

1. Open a Safari browser window.
2. Select the “Safari” menu, and then select “Preferences” from the drop down menu. 
3. The preference pane will open and then select “Security” on the top row.
4. Uncheck the checkbox "Block pop-up windows". 
5. Close the Preferences window.

From your tablet or iPhone:

1. Open the Settings app on your device
2. Select "Safari"
3. Under “General”, locate “Block Pop-ups” and slide the button to the disabled position in order to allow pop-ups.