Welp! Offer Acceptance Deadline

I just received my unconditional offer letter for MS in CS advanced entry at Usyd Camperdown/Darlington Campus on 8th Dec as an Indian Student. As no specific deadline was mentioned in the offer letter, I could only come across the generic 10 business days deadline advised. But to accept the offer, I have to pay atleast 25k AUD but my education loan would be sanctioned in 12-13 business days, so is it necessary to pay within 10 business days itself or can it be bit more flexible?Also if anyone could share helpful emails of the university, since the contact number is not accessible,to raise this inquiry and get consolidated reply would be deeply appreciated.