Key words there are credentialed and permissible purpose.
In other words, it's an automated way for me as an employee to have my employer verify my employment and/or salary information—not necessarily both—without having to hunt down someone in HR. This is particularly useful for previous companies where I no longer have access to internal systems.
I have used it most commonly for mortgage applications.
I can log in and generate a one-time or limited-use code to provide access, and select which data I want to provide access to. I then provide that key to the third party, who verifies with Equifax.