Doesn’t seem to be ready for WordPress 4.9.4

I tried this plugin with the latest verison of WordPress (currently version 4.9.4) and the results were disappointing. On submitting a trial request, unwanted code is returned across the user screen. Also, on requesting to read more, I find that the remaining text does not sit properly within the page design for theme Twenty-Fourteen. If anyone could suggest an alternative up-to-date free plugin that is ready to run with the above theme and version of WordPress, I would be most grateful.