The first question to ask, do you have an external monitor attached to your computer?
In this case, if you are not able to enter your email into the Group Funnels Chrome Extension or mouse click on anything chances are it is because you are looking at the webpage with GF ext on the external monitor.
There are two options for you:
1. use your TAB key on your keyboard to navigate around the GF ext
2. Move a webpage to the default monitor (computer/laptop--NOT the external monitor)
chances are, you will then be able to use your mouse to click all over the GF pop up window.
Dont forget to click on the BLUE SAVE button to save once you enter your email ;)