Elizabeth stubbs

Hey so I've got a Mac desktop computer that I've had for a while now but it still works very good. I have Minecraft and the latest version installed and have been trying to download forge so I can play a modded version, my problem is after following all the video instructions and written instructions and everything forge just always says error right after it downloads. The first image shows forge before I try to fully download it, as you can see everything looks right and then when I try to click ok it loads and then says the second image the error thing and just doesn't let me download. Ive done everything right I don't understand why it's not working. Has anyone ever had this problem or just knows how to fix this. Im desperate for help I've tried so many things. Thanks