Once you hit
"Send", the room will send you an auto-response that it has accepted
your meeting.
If there's a conflict, it will send you an
auto-response that it was already booked.
Note: ALWAYS check the auto-response to see if it was
accepted/declined. Especially when
scheduling repeating meetings, because if you schedule a series of 4 meetings
and one overlaps with an existing meeting, NONE of your series will be booked.