What's the requirements for the purpose of Germany...

In Saudi Arabia, the Embassy and Consulate General of the Federal Republic of Germany are responsible for issuing visas.
The local responsibility for issuing the visa rests with the mission responsible for the region in which the applicant is located (residence).
The embassy in Riyadh: the central and eastern region, which includes the Qassim Governorate, the Eastern Province, Hail, the northern border (the northern region), Al-Jawf and Riyadh.
The Consulate General in Jeddah: Tabuk, Madinah, Makkah, Al Baha, Asir, Najran and Jazan governorates
The competent German mission decides on the issuance of the visa, taking into account all the circumstances of each individual's application. There is no legal requirement to issue a Schengen visa. In each case, the assignment must demonstrate that the following conditions have been met:
Clarity and validity of the purpose of travel to Germany
Financing (bearing) living and travel expenses
The willingness of the visa holder to leave the Schengen area before the visa expires
A medical insurance document valid for the entire Schengen area and for the duration of the stay with a minimum coverage of 30 thousand euros
If the applicant is unable to finance the trip and accommodation from his own funds, a third person may undertake to cover all costs associated with such trip in accordance with Articles 66 and 68 of the Residence Act. This undertaking is submitted to the aliens authority at the place of residence of the person making the undertaking.
A visa cannot be granted to persons whose entry into the Schengen area would endanger the security or public order in the Schengen states or who do not fulfill one or more of the above requirements.
If the application is rejected, the applicant will be informed of the relevant reasons. Legal resources(s) are available to all applicants