The connection is not complete until you change the initial password
The Getir Çarşı setup has an unusual step: the initial password you are given is temporary and must be replaced, via a reset call, with one you choose. Skip it and the setup does not count as complete. Since it has no counterpart on other platforms, it is easily overlooked.
There is also an integrator name that must be sent on every request. This field cannot be left empty — the "a default applies when blank" behaviour seen on other platforms does not exist here.