Well, if the the plugin is not necessary for importing content in the future and is meant to provide a demo, then I will not attempt to install it again. Maybe there is some incompatibility with another plugin. I am not sure if I can revert back to the old PHP version and run it through the scan.
Anyway, thanks for the support. I just wanted to let you know there might be some issue with the plugin, but it is probably something I did on my side.