Hi, I use InitialInventory-fabric-1.18.2-6.0.8.jar on my fabric 1.18.2 (0.14.6) server.
I want to know where I have to create the config file?

Is it /scripts?
And how should the file be named?

The mod uses CraftTweaker for functionality, you can find out more about scripts files here
https://docs.blamejared.com/1.18/en/tutorial/IntroductionToScripting/WhatAreScripts

They can have any reasonable name as long as it ends in .zs

If you need any help, you can join https://discord.blamejared.com and ask there as well