Hello,
You provided WP Dashboard access only. But we need also FTP access to check the compatibility of the mentioned plugin with the single product builder. The message displays if built-in layout used https://prnt.sc/26r90z2
So, provide us with FTP access. If you don’t know what FTP is then contact your hosting provider. They will be able to give you FTP host, FTP username and FTP pass. We’ll be able to proceed only after that.
Regards