How do I access the Unreal Engine source code through their Perforce server?

on this page, Downloading Unreal Engine Source Code | Unreal Engine 4.27 Documentation.
it says that If you are an Unreal Engine licensee, you can access the source code through our Perforce server instead of the public GitHub repository.

Can someone please share how to do so? I cannot find the answer anywhere.

Thank you very much in advance.

Did you solve it?