Shed roof over balcony!? What should be considered?

Good day. I hope I am in the right forum. My balcony on the upper floor is unfortunately not covered. Above me is a roof terrace. Below me is the ground floor. The balcony extends 5x2m to the south side and about 2x2m over to the east side. So, a kind of L shape. I want to cover the balcony door on the south side with a kind of shed roof 3x2m. A simple steel construction with plexiglass panels and a small gutter at the front edge of the balcony (so that the water does not run down to the neighbor). Under the shed roof I want to hang a sun sail in the summer. So nothing big. Protection from rain, sun, and snow in front of the balcony door. Next to me I also have a neighbor with the same balcony but southwest. He is also considering doing something. Who can tell me what to pay attention to? Should I go to a metalworker first, or to the municipality first regarding the need for a permit? Or a structural engineer first? My balcony floor is a "Light granite slab". Looks like a hospital floor. Also does not make a very "stable" impression. Possibly I will have a decking floor installed as well... The shed roof should therefore be attached to the wall around the balcony door and at the railing in front. Who can please give tips here? Thank you very much erika

The house community must agree to this, as the exterior facade is being changed.