Doing a 2nd internship after Graduation

I have graduated from my Masters in June 2025 in Paris..and I have still not found a job so I'm deciding to do another internship.

Now, I have found a very good internship but they HR told me they will need a contract from a School/university.

I know that there are some websites were I can get a school internship contract by paying a fee of 200€ - 300€ and taking a course of 200hrs.

Has anyone done this before and How do you communicate this to the HR and will this type of contract by online course websites be valid??