Coming soon Pro is a commercial plugin so I’m afraid I don’t have access to the code to investigate this properly. This is beyond the scope of the free support I would normally be able to provide, however I have had a look at the demo online at the vendors site and I suspect that the popup.js javascript in Alligator Popup is not being included in the head section of your coming soon page. It looks like this can be added in the ‘design’ section of Coming Soon Pro.
I don’t now whether the following will work, but what I would suggest trying first is to view the source of a normal page on your site where alligator popup is working, select the line that looks like the one below and copy it to your clipboard:
<script type="text/javascript" src="https://your site url/wp-content/plugins/alligator-popup/js/popup.js?ver=1.0.0"></script>
Then, in the coming soon pro plugin settings page, go to the design tab and paste this line into the code section somewhere between the <head> and </head> tags.
If this doesn’t work or you need further help, you would need to ask the Coming Soon Pro plugin’s vendor for support as they will be better placed to help you with their plugin.
