1.13.2 doesn't have that task.
If you're using intellij IDEA it will be done when you import or refresh the project.
If you're using eclipse I think it happens when you run the eclipse task (My info may be outdated with this bit, if anyone else is more up to date please correct me).
Sounds like you're playing a vanilla server with a Forge client.
Have you made sure you:
Installed a Forge server
Ran the Forge Server jar and not the Vanilla Server Jar
Have the same mods installed on the server that you do on the client
When you say crash do you mean freezing or does it boot you back to the launcher?
Also you appear to be trying to use Pixelmon for 1.12.2 with Minecraft 1.13.2, this will not work.
When you say you got the modpack from FTB, did you make sure to get the server version of the modpack or did you just copy the files from the client version?
Did you also make sure you got the Forge version the pack was designed for?
I should mention we don't provide support for 1.7.10 anymore because of its age.
If you want to us to continue helping you with troubleshooting please update to a modern version of Minecraft.
How about this, if your keyboard has a key that says "Prt Scr" (Print Screen) or something similar, press that to copy your screen to your clipboard, then use Control + V to paste it here.
If you've managed to corrupt a feature of Windows you probably have bigger problems than being unable to install Forge, please prioritize getting those bigger issues fixed first.