Explanations abound but I can't find a single translation. I would therefore just go with this perhaps with a translator's note (a reference to Belair)
I prefer portfolio and if you read the reference, dossier progressive is sometimes called dossier portfolio too.

Just a suggestion. "progressive" makes me think of political parties. I'm not sure in what sense portfolios might be "progressive", except that the number of the portfolio progresses with time, which is in any case obvious from the fact that they are numbered. So the word "progressive" seems to me to be superfluous. I wonder whether "consecutive" might be a better translation of "progressif" in this case.

yes, the "progressif" refers to the fact that this portfolio is used for showcasing/assessing the student's progression through the course.

Initially I was about to agree with Gordon that portfolio on its own is OK, esp. when already numbered but I think it's necessary to say what TYPE of portfolio it is as otherwise it could be ambiguous. Or clarify elsewhere that this is a

Portfolio (of work) for evaluation/assessment

https://www.edglossary.org/portfolio/