I can't get in touch because the product isn't listed in the plugin author's forum.

Reactive Search Pro --Advanced WordPress Search Filter Map & Grid
I bought a plug-in called.

It’s like asking a question in my own forum, but I didn’t have Reactive Search Pro in the checkbox to select the product to ask.
I get an error when I select another product and enter the product code.
How can I contact the creator in such cases?