To have access to the Group Chat feature, you must be on the Ultimate plan. However, you may also have access to it if you're on the Growth plan but it will be as an Add-on feature for $10 per month.
To gain access, please follow the steps below:
Go to your profile icon and look for Extensions
Add group chat feature
Once you have paid for it, it will be automatically added to your Kahunas coaching account.
Here's a Loom video on how to access and create Group Chat: https://www.loom.com/share/71ecfe31dbb64237aeb38141983ad116?sid=8de8f5bf-50e2-4872-b022-629ff2428a32.