To start with understand that Mr. Mabo was not an "Australian Aboriginal" although he is from an Australian territory and is a native of that territory. He is a "Torres Strait Islander" from the islands north of Australia. The culture on these islands is different from that of mainland Australia. They even have different flags to represent their people, Mainland Aboriginals were hunter-gatherers** without land ownership as traditionally understood in Europe. There were territories, belonging to particular tribes, but an individual person referring to "his" land would not make sense. His people's land of course he'd know well and there would be no confusion. Torres Straight Islanders on the other hand farmed and their land law was very different.
An example of the sort of way land was managed was this extract from a letter from Mr. Mabo to Mr. Dipoma.
"Your letters are full of what normally drops off in your toilet after a good feed. My adoptive parents claim me alone as their son. You have no claim for that land. Now I'm telling you to move out or you'll be thrown out by force. "
This is an extreme example of course but it shows the basis of Torres Strait Islander land law. This is my land, get off it or I'll hurt you. There's no mention of traditional ceremonial purposes, only of a) inheritance, b) ownership and c) potential violence if a) and b) aren't respected. Eddie Mabo wanted something that is indistinguishable from free hold title. He didn't get this. He never owned the land the should rightfully have inherited and his children didn't get it either after his death. Instead tribes, mainly not Torres Strait Islander tribes, acquired completely novel and bizarre rights to some land. These included a "right to negotiate" over development, not a right to veto it, or even be paid to allow it, This was a fundamental betrayal of what Eddie Mabo was and wanted. If he had been a white man his descendants would have had freehold title to his land. He was betrayed in the most racist way possible.
* Well it changes a lot so it's not a good test.
** With the exception of one possible aquaculture setup, the only example of a culture developing aquaculture before agriculture.