Every indigenous tribe has its own criteria for determining membership. For example, the Navajo Nation requires at least 25% Native American blood, while the Comanche Nation requires at least 12.5%.
It’s important to note that having a particular percentage of Native American ancestry in your DNA is typically not enough to claim tribal affiliation. Many tribes consider membership based on your documented family history and participation.
Using tests from companies like Ancestry are best suited for satiating your curiosity about your lineage or to get hints about where to conduct further research.