Application – proof of mandatory internship?

Hello, I'm doing a one-year internship to obtain my university of applied sciences entrance qualification. A company I've applied to requires proof of mandatory internship. The problem is, there's no proof available.

However, I still have to somehow make it clear to the company that this is a mandatory internship. At most, I have a few sentences from a PDF from the state of Berlin (I also live in Berlin) that explain that this internship is mandatory:

" The internship to obtain the vocational component of the university of applied sciences entrance qualification is a mandatory internship pursuant to a provision of educational law (here, Section 46, Paragraph 4, Sentence 2, Number 1 of the VO-GO) within the meaning of Section 22, Paragraph 1, Sentence 1, Number 1 of the Collective Bargaining Autonomy Strengthening Act (Minimum Wage Act), which entered into force on January 1, 2015. The employer must verify the intern's statutory insurance obligation."

Is there any way I can include this in the email? How do I tell them? Does anyone have any ideas?

Best regards and thank you!