so you have to use jitsi in your WordPress using IFrame and create a page php , get Group plugin to restrict who can see this page.
I use a plugin called: content control for wordpress. It will allow you to restrict a wordpress page to only logged in user or a user profile. If you use buddypress or buddyboss you can also get a plugin called BuddyPress Group Tabs Creator Pro which will allow you to create a tab in the groups page where only group members can see the tab and when you click on tab it opens up jitsi embeded with shortcode using another plugin named : WP JITSI SHORTCODE.
Hope this helps