It is possible to integrate a Discourse site with WordPress with the WP Discourse plugin. For example, the WordPress site can publish posts to the Discourse site. You can also integrate authentication between the two sites so that users login to Discourse from WordPress using DiscourseConnect.
The main thing to be aware of is that WordPress and Discourse need to be hosted separately. They can’t exist on the same domain. A common approach is to serve Discourse from a subdomain of the WordPress site’s domain.
With DiscourseConnect enabled, you can link from WordPress to Discourse using the method outlined here: Create a DiscourseConnect login link.