Volvo S40/V40 BJ2000 Radio Exchanges

Hello dear community, At the moment I am using the original cassette radio from Volvo in my elk, which I want to replace so slowly. I have already bought a Radio DIN2 from JVC. I was aware that it will be different on the radio but I will not find it at Amazon etc.. Which adapter do I need exactly? I have the same problem with the antenna cable. Now to my second request. The mounting frame from the radio does not fit in the shaft, because Volvo has attached “rails”. Have already read here that you have to saw it off so that the radio fits in. Is there another alternative? Please have mercy with a Volvo beginner! Thanks already for the answers!