Hey Igloomy,
first of all, thank you for the purchase!
This hasn’t been reported before, yet let’s try the following: please download this archive of the plugin, unzip it, and upload the contained folder (not just the files within it, but the entire folder) into the plugins directory in your WordPress installation: /wp-content/plugins. After that please refresh the admin of the website and go to the “Plugins” section. There you should be able to see the “Contact Form” plugin – hover over it with the mouse and press “Install”. Please let me know if this fixes the problem!
Sincerely,
Andrii / Satori Studio