I am looking for a supervisor professor for a PhD thesis in Polish universities

I have been trying since June 2019. through email, I also called a phone, but I could not achieve that yet. Can someone help me, please ?

* Polish universities recognized by the Iraqi Ministry of Education and Scientific Research (2020/2019);
- University of Warsaw
- Jagiellonian University
- AGH University of Science and Technology
- Adam Mickiewicz University
- Medical University Warsaw
- Warsaw University of Technology
- Medical University of Silesia
- Lodz University of Technology
- Nicolaus Copernicus University
- University of Lodz
- University of Wroclaw
- Wroclaw University of Technology
- Cracow University of Technology
- Poznan University of Technology
- University of Gdansk
- University of Silesia
- Wroclaw University of Science and Technology (WRUST)

thank you so much at all

I may be mistaken, but is it really possible to engage a supervising professor if you are not actually enrolled in the university? I mean, you just cannot expect that some professor will take you as a student if you are not a student at the place he/she works at? Maybe it could work in public universities if you meet some criteria, but still.. the process must be established by laws or something.