Access denied. Join hub site

Hi all,

I´m trying to add new created sites to a hub site through Microsoft Flow/Power Automate. 

The user who is set as connector is a SharePoint Admin and has full control on both sites as site collection admin. 

There is no limitation for the hub site. 

"status": 403,
  "message": "Access denied. You do not have permission to perform this action or access this resource.