The real estate office will not give me an advance copy of the residential condo lease so that I can review it... is that legal ?

Legal?  Yes.  However you should never sign any contract or agreement (including a residential lease) which you have not had an adequate opportunity to review and understand.  Many residential leases have a clause at the end of them which expressly states that you have had the opportunity to review the Lease Agreement and to have to reviewed by Counsel.  Make sure you avail yourself of these rights, and do not sign any Agreement unless and until you are comfortable.