License key is not accepted

Yesterday I bought Product Filter for WooCommerce (XForWooCommerce), but the license key I got is not accepted. I cannot contact their support, I cannot open the documentation, …
I have to connect with Envato, but then I get the message “Sorry, you haven’t purchased any of our products from Envato”.
I do have a License Certificate from Envato, item ID: 8514038, item purchase code: d1bc7ff6-0af5-…etc
How can this be solved, please?
Kind regards

You should contact the author of the item for clarification… but at a guess, maybe you’re trying to activate the free bundled plugins?

If so, you would get such a message as you need to have bought the full version of the plugins to get automatic updates and premium features. They will work just fine without a license key though, so you can ignore that step.