Hi
Vagnervarg,
Joao Afonso das Grotas Fundas lived in the 1400 and 1500s. Autosomal DNA tests (like My Heritage, Ancestry, 23&Me, and FTDNA's Family Finder) do not reach back that far. They reach back about 200 years from the testee's birth. In order to obtain some of Joao Afonso das Grotas Fundas' autosomal DNA, the tester would need to be born about 1700. No one alive today was born c. 1700.
However, Joao Afonso das Grotas Fundas' Y-DNA may still exist. The test taker needs to be the son of the son of the son of the son, all males all the way forward, to a living male today. A strict male line. If that's you, then yes, you need a Y-DNA test.
Cheri