Hi witeman
This link should give you the answers your looking for



www.police.sa.gov.au/online-services/cross-border-travel-application

Can we enter South Australia via Victoria if our travel (via car) originated in New South Wales? What roads can we use? Yes. A person from a low community transmission zone can enter South Australia in a vehicle from New South Wales via Victoria if the person travels directly through Victoria without leaving the vehicle and only via the Sturt Highway from Mildura to Yamba or via the Calder Highway and Meridian Road between Abbotsford Bridge and the Sturt Highway and then via the Sturt Highway to Yamba. We are driving from New South Wales to South Australia. Are there any reasons we could stop in Mildura? People who are driving from New South Wales to South Australia, who need to travel via Mildura should refill petrol/obtain supplies in New South Wales to avoid stopping. A person must avoid stopping in Victoria unless for an urgent, pressing necessity and if so, avoid any non-essential contact. Examples for stopping would be for a sick child, flat tyre, or you are required to do so under Victorian law. Upon arrival at South Australia, police will ask to verify your travel movements and confirm that you have travelled directly from a low community transmission travel zone. FAQ via Australian government Covid-19 app. In addition you need to register your plans either online via that same app preferably 14 days prior, or at the border

Yes you can travel from nsw to sa but you need to apply for permit online sa police 14 days before travel and you must travel from mildura to yamba ,sa. And you are not allowed to leave car except in emergency, i have just applied and got ok we will travel next week to wilpena pound from central coast. Happy travels.