Welcome to the forum.
The requirements for the 915-928 MHz are in the Austrlian Radiocommunications (Low Interference Potential Devices) Class Licence 2015, Compilation 2, updated on 27 June 2018 (latest version as of 13/8/2019). Frequency Hoping transmitters, point 58, 915-928MHz transmitters have a maximum power of 1 watt (EIRP) and must have a minimum of 20 hopping frequencies. There’s no duty cycle requirement in Australia that I can find.
https://www.legislation.gov.au/Details/F2018C00500
If you were using The Things Network they do have requirements but you said it’s point-to-point.
p.s. I actually thought there were duty cycle requirements in Australia myself until I looked up the legislation.
