If you have been told by the an immigration officer from the Department at 55 Currie St, I suggest you get the name of the person who has given you this advise. If you don't have a name then, call this number, 1300 364 613 and tell them your problem. If he tells you t make a paper application, be sure to note the name of the person you speak to, time and date. It is a long wait for someone to answer the call but believe me it is better to wait on the phone then to go to the immigration department. If they say to you to make a paper application, here is what you must do. Print-screen the error message that you are getting when you try making the online application and save it. Attach a copy of the print-screen error message when you e-mail your application, so they know why you are making a paper application. Be sure to fill out application Form 1276. I will send you a link to the form that you can use. The one that is on the Immi website is different because it is the new one for Graduate visa applicants
Although they say paper application, they prefer the application and all supporting documents to be attached and e-mailed to them. This is the address to e-mail your application to but PLEASE DO NOT SEND AN APPLICATION until you have instructions from the immigration department, otherwise, it can be rejected. Paper application e-mail is: firstname.lastname@example.org. When you have sent it to them, it may take a week to 10 days for them to send you an Acknowledgement of valid visa application and Bridging visas. If you don't get one, than call them and follow up.