German

You need JEE Advanced cleared or 1 year of study in reputed university of India like NITs, IITs, etc.

You have to complete a Bachelor's degree in the university, which are recognised by Germany.

For the entrance exam, you need to have knowledge of basic and applied grammar, besides some competence for simple translation from the language concerned into English and vice-versa.

You can prepare according to Syllabus, you can find the syllabus from this link:
http://jmi.ac.in/studyatjamia/Syllabi/entrancetest.
You can prefer various books like Arihant preparation books etc.

Hi, Eligibility: In order to pursue a Bachelor's degree in any foreign language, the candidate must have cleared the higher secondary school certificate or 10+2 from a recognised board. The duration of the Bachelor's course is mostly three years. https://www.shiksha.com/humanities-social-sciences/languages/colleges/german-colleges-india.

JEE Advance is not a basis for gaining admission in German universities. They have their own policy and procedures. Please visit the related German University's website for more accurate details.

I Suggest for WILDAU.
Maybe then, you must go for FH Aachen, I was unaware of that fact.