Your popups may not appear for multiple reasons, to make sure all settings are correct, please check:

Is the embed code is properly present and installed in your website pages source code?
Is the campaign enabled/activated?
Is at least one variation is enabled/activated inside your campaign?
Does the popup contain content inside it (i.e. its not an empty template).
Is the domain name assigned correctly, e.g www.domain.com or subdomain.domain.com?
Is the popup targeting set up correct?
Is your domain name linked only once to your Wishloop account? Avoid linking the same domain name multiple times, only once is sufficient to manage all your campaigns.
Have you opted in already? The campaign can stop working/displaying (just for you on your computer) if you opted-in already by completing the optin form, as there is no reason to keep showing it for you because you already took action. To properly test if it is working on not, please try in the private/incognito mode or clear your cookies. (see here how to better test your popups).
If your website is based on WordPress, please check that the Wishloop plugin is installed, activated and setup using your USER ID.

If you've checke all of the above and still having probems, then please feel free to contact us.