I want the buyer to be able to fill out the application form on the website and after that the opportunity appeared in the CRM. I understand how to do this.

Next, I want there to be an online chat between my buyer and the manager. All messages should be associated with the CRM opportunity and displayed inside this page.

This can be a conversation at the bottom of the page (like an email in the Sales app) or on the right in the list of activities.

How to do it?