Problem with BL Touch

I followed this guide https://youtu.be/U98V1nMwLKk

in the start i tried to use th3d firmware but I didn't quite understood what to do so I downloaded the latest marlin firmware (2.0.7.2 if I'm not mistaken) but I got a lot of errors while compiling it in the arduino program so I used the same version of marlin as he did in the video and that worked, but my bl touch just slams into my bed every I try to auto home or do a thing with the step by step of the uni bed leveling (when I turn it on all I here is a sound and thats it) I tried raising the z axis higher and pushing the bl touch manually with my finger and it worked and stopped and tried again but it isn't stopping when it slams into my bed can someone please help?