In the following link you can download Brazilian PNAD's unemployment rate
You can use the series freelly but it is mandatory to quote the source.
Full description of the methodologhy is discussed in the following link: Estudos Econômicos (portuguese).
Suggested citation:
Bacciotti, R.; Marçal, E. F.; Taxa de Desemprego no Brasil em quatro décadas: retropolação da PNAD contínua de 1976 a 2016; Estudos Econômicos; USP, volume 50, number 3, pages 513-534, São Paulo, 2020.