Thanks tjaded and Jeff.
After more research I figured out that the lever for changing the exposure is missing :/
I found yet another one in the meantime! A Rolleiflex 3,5 F from the looks of it.
One with the knobs in front; everything seems to be fine except the shutter release button doesn't work :/
I won't be able to take them to the festival for my project but at least I have something to get fixed/ or fix on my own when I get back
I can't believe all this time I was trying to save up for a medium format my dad had two hidden at home rusting in a box!
Just out of curiosity, does anyone know the trick of fixing shutter release buttons on these things by any lucky chance?