How can I book a seminar room for my X-Student Research Group?
Please contact the institute/department to which your X-Student Research Group is institutionally affiliated for room booking. The professor who signed the application form for institutional affiliation can probably support you here. The professor has agreed to support you in this context with his or her signature.
In any case, it is important that you tackle the question of room booking early on, i.e. ideally as soon as you have received your funding commitment.