Translation:Would you work as a sales associate part-time?
Good question. All I can say is that throughout this and the previous subject set which also dealt with this tense, the -ing version of the verb hasn't been used. That suggests that in this case (literally!), there is no option for it.
In this sentence, it gives the impression that someone at a job centre is asking if the job seeker would be okay with working part-time. If that's the case, "would you be working..." wouldn't fit. If it were a friend asking after a job interview about the job, it would - in English. How the French verbs work in that instance, I don't know.