The French route still requires three years of pay stubs and tax returns and getting a job (and showing stability and integration, particularly professionally) after those two years of study, meaning it comes back to the standard five years of residency (plus the time to submit everything, go in for an interview, and get a response).
France does not reduce time to permanent residency for studying. In fact, student visas don’t even count towards residency for PR. It does technically reduce the time to citizenship, but the other requirements just make it so that your time as a student counts towards residency for citizenship. And naturalization takes years in most cases.
In any case, all that requires actually getting a job after your degree which (while I don’t know your field well) would likely require fluent French, which takes a loooong time if you can’t make it your primary activity. Doesn’t mean you can’t come to study or that it’s totally impossible to stay after your degree, but just wanted to inject some reality on the immigration front (because honestly it is brutal to live through so best to be prepared).
Is your arrival date after the visa start date? That’s a big error I’ve had people have (entering before their visa because they were visa-free but then not being able to validate unless they lie or actually leave and re-enter properly). Otherwise it may be a website error. There’s usually a way to contact the relevant service (it’s been a while since I’ve had to validate a visa and never had this issue, so I can’t tell you exactly who or where or how, but clicking around on the website usually turns something up). This is a great example of « don’t put the thing off till later » particularly when it comes to France and anything that involves a website.