Thank you for taking your time to write to us.
Could you please provide us the email that you used to purchase our product? ForumEngine is a theme that will be set like a site (E.g: http://demo.enginethemes.com/forumengine). It’s not a plugin that you can integrate to your current site.
Also, please use your customer account and submit a ticket with the account info to get our full support. If you bought our product through ThemeForest, you just enter the purchase code on your profile to update your account to the customer here.