At the moment, Wix does not support the capability of setting custom MX records. This means that you cannot add the required MX records in Wix to setup a reply-to email with Plutio. In order to add the required MX records you will have to move where your DNS is managed.
Note: This will still allow you to use Wix services. You will just be moving the DNS management to a different provider. During this process, you will have to pay the new provider for these services. Google Domains is a popular service.
Please consider transferring out of Wix domain services.
Once you have successfully moved your DNS to a new provider, please continue:
Set up Custom Reply-to Domain
You can customize this reply-to email/domain by following these steps.