Hi D,
If you're using our Master templates, there are already actions created to catch Global Events to disable and enable the next button (or all of the navigation if you prefer):
https://www.screencast.com/t/3cVjm7Jt4d These already exist, so you don't need to set them up.
To use them, on a regular page, you would create actions like the following (in this example, we're disabling next on page load, and then when they have completed the activity on the page (clicked the right button), we enable the next button):
https://www.screencast.com/t/wFswVNIociHope that helps!