@Amin02, thanks for reaching out 🙂
Are there definitely others in your apartment complex with an active NBN connection?
Does the address appear on NBN's rollout map. Pop in your address and let us know what shows up → www.nbnco.com.au/Check-Address/Rollout
I do often come across addresses that haven't been logged on NBN's side. The provider can raise a missing address dispute and NBN will go ahead and register the address.