Short answer, Rusto primer will work fine for overcoating with acrylic paint.
So is it acrylic or oil based? I don't know. What does oil based mean? Does the word 'oil' refer to the solids in the paint or to the liquids?
This particular paint is certainly acrylic. The film former is an "Acrylic Modified Alkyd" according to their TDS sheet. But the paint also contains solvents such as acetone, xylene, and naptha. So the paint is perhaps best described as a solvent-borne alkyd/acrylic.
The TDS sheet refers to the paint as an "Enamel spray," but don't let that fool you. The word 'enamel' is a misnomer as 'enamel paint' does not contain enamel. 'Enamel' is a marketing word, not a technical one. Go figure.
Chris