What
@orrire was referring to is that there is a maximum number of players allowed on the PTR at the same time; when the server is full, there will be a login queue.
However, anyone can freely create an account for the PTR server -- but this only makes sense when a public test is running. Right now, none of you can access the PTR server since no public test is running.
Public tests will always be announced via a changelog in the
PTR Changelogs section, as well as in the latest Dev Shack thread, and they will usually run for just a few days.