As far as I know, it means exactly that. For migration you need to have a qualification that is accepted by the Australian authorities.
In Physio, this means that you need to have registration from the Physioboard of Australia. Once this has happened, you can apply for the skilled migration category.
Without conditions means that you have to be fully registered. Australia offers 'limited registration' to Physios who are considering going for the full registration or just want to gain work experience in Australia. They are allowed to work under supervision at a designated clinic.
Hope this helps,
Fyzzio