I'm wondering if this plugin is an abandoned project. For one, it hasn't been updated in over a year. If a plugin hasn't been updated in that long, then most often it means the project has been abandoned.
I installed the plugin, however, it requires you to enter an API key. The description tab on here gives a URL for one to signup on as there's supposed to be a free version. Unfortunately, that brings me to a somewhat blank page on their site with the title of "Nothing found for Members Signup."
I did contact support in regards to the matter. I gave the low rating even though I've contacted support due to how unprofessional this company seems. I say this due to their plugin requiring registration and their signup page that they link to is nonexistent. Basically, the plugin nor their website work.