Can’t link merchant center from aggregator account

We run a multi merchant center aggregator account and i’m attempting to link to one of our sub accounts using my admin user from the aggregator account which has full access to all sub accounts.

However, the only accounts that show up when configuring the plugin are merchant accounts where my email is added directly to the account access section, I don’t see any of my aggregator accounts in the list.

Any idea why this won’t work?