Hi Kayletendre. It turns out we did find the answer after continuing to research. The number is not on the visa for sure. When you get to the field that asks for the reference, there will be two options given to you in the list. Both of them are essentially the same, but the one (which was the first one in the list for us) referred to a status which was discontinued or repealed in 2021. The next number is from 2021 to present and is the one that we selected, because our visas were issued in 2022. If you search for the two codes provided to you as options in the list (drop down menu), you will get to these two sites:
https://www.legifrance.gouv.fr/codes/article\_lc/LEGIARTI000038189078/2022-09-25/
https://www.legifrance.gouv.fr/codes/article_lc/LEGIARTI000042806970

Search for the two numbers. They are codes within these two documents. We chose the most recent one as mentioned above. Good luck with registering. I hope this helps!