This depends sub leasing rules are different with each company. Some companies make the original lease holder stay on the contract and they would just add your name the sub-leaser on as well. If that is the case than the original lease holder would still be liable and responsible for paying the rent if you failed to do so. That is if this contract is one lease and not leased by bedroom. This is not very common and for renters not the best way to do things but some companies do handle sub-leases like this.
However if the company was able to sign the origianl tenant off the lease and sign you onto a completley new lease than you are now responsible for the rent as it is a legal binding contract.
I would talk to the managment company and the previous lease holder to try and work something out!