I am really new with QGIS
I have a quadratic grid with different populations in each square and I have made polygons with the ORS plugin. The polygons cover some squares in full and some squares only partially. I need to count how much of the population is in each of the polygons. I am fine with assuming that the population is evenly spread within each square. I have tried to do that with MMQGIS, but I could not go further for my next step.
I am wondering if there is any other tool or way to do this. I hope to be able to do it automatically since I have to do it with lots of polygons.