Is it permissible for us to delay the congregational prayer in the prayer hall by half an hour after the unified Adhan, or should we pray immediately after the Adhan, knowing that most employees are outside? And is it permissible for me to pray alone after the Adhan if I wait an hour for them?

There is no harm in the worshippers agreeing to delay the iqamah (call to commence prayer) or setting a specific time for it, as long as that does not cause the prayer to go outside its prescribed time and it is more convenient for the worshippers, leading to an increase in their number, even though praying at the beginning of its time is better. This ruling is general for a musalla (prayer room), a mosque, and other places, and it is not affected by linking the musalla to a unified adhan (call to prayer) system.