"My dad is an actor."
Translation:Мій тато - актор.
This depends on the definition of 'correct'. It's grammatical, but sounds less natural in Ukrainian as spoken in Ukraine. This course teaches Ukrainian as spoken in Ukraine.
BTW, is the version "Мій тато є актором" possible in real life speech?
Yes. I'm not completely sure about colloquial speech, but it's used in formal texts a lot.