According to Portuguese law, the holder of a resident permit - including the Golden Visa card - has the right to access the following fundamental rights in the same conditions as Portuguese citizens: access the Portuguese education; to work as an employee and to be an independent worker or entrepreneur; access to the national public health care system; access to the courts and to a due process of law. Regarding the employment conditions, this is reinforced by Portuguese labor code which forbids any kind of discrimination on its article 25º and the article 24º, stating that "employee or the candidate has the same equal opportunity rights and treatment regarding employment, work formation and promotion of professional careers as well as working conditions, and cannot be benefited, privileged, prejudiced, suffer privation of any right or be exempt of any duty due, namely, to ascendency, age, gender, sexual orientation, gender identity, civil status, family situation, financial situation, grade of instruction, origin or social condition, genetical heritage, diminished working disability, mental or physical disability, chronical disease, nationality, ethnical group, origin country, language, religion, political convictions and ideologies, labor union affiliation, and the Portuguese government is obliged to promote such equality." So, you do not need to apply for any special working permit and your Golden Visa card is sufficient.
