I've tried to start the project and i had a bunch of errors i fixed them and then i have that pls help :

Failed to apply plugin [id 'forge']
You must set the Minecraft Version!
> java.lang.NullPointerException (no error message)

PS : it was with the 1.7.10 version.

Based on the error, I am assuming you did not set the Minecraft version in the build.gradle file properly (no idea how you can do so, I haven't touched 1.7.10 in a long time). You could also try deleting the .gradle folder in your user directory, or using a different Forge version. You can also download the 1.7.10 Forge "Src" file for the version you're using, and compare the build.gradle file in there with yours.

As we no longer support nor maintain the 1.7.10 version of SecurityCraft, we can't assist you any further, I'm afraid.