To allow pop-ups on Safari, users can enable this feature on both Mac and iOS devices. On Macs, they need to navigate to Settings > Websites > Pop-up Windows, select the website, and choose "Allow" from the dropdown menu. On iPhones and iPads, users toggle off Block Pop-ups in the Safari settings to allow pop-ups for all websites. Users can also temporarily disable or enable pop-ups on their devices by adjusting settings in Preferences or disabling Block Pop-ups. It is essential to ensure that pop-ups are enabled only on trusted websites to avoid security risks.