So, sometimes you get the red connection banner of death - meaning the sub-account is not connected to GoHighLevel. GoHighLevel oauth2 / api v2 connection is complex but we account for every version of it in v2.1. Here is a full walkthrough of every step from an agency level on how to connect and secure connection to all sub-accounts that you manage.
The only one missing is the sub-account level connection which is just under integrations and follows the same idea as the direct connection.