Okay, so I just purchased the god damn license without really understanding this stuff. I though I would get a different download or something, but no… Then how the hell am I supposed to edit those files?
Thanks for reaching out and sorry for the frustration here.
To answer your question, that theme is not a WordPress theme. Usually as a fast way to confirm this, you can use such a tool to determine this (https://www.wpthemedetector.com/). The template is basically a pure HTML,jS and Bootstrap CSS powered. To edit it, you can use an editor of your choice such as DreamWeaver or Sublime Text. You can edit the HTML files to your preference as these represent the various pages.
Please let me know if you have any questions on this.