Unfortunately, it’s not proper Open Banking.
It’s called a “Modified Customer Interface”, and is essentially like screen-scraping, only with the third party (Emma) having to login through a “special” login page.
You have to share your credentials and it is not as reliable as an API. I believe that Emma have publicly stated, in the past, that they will only support API providers going forward as they don’t have the ability to securely store login details on their current infrastructure.
Metro Bank are the same, and stubbornly refuse to provide an API.
Co-operative Bank have written more about it here if you are interested.