Large World Enabler is a tmodloader mod. TerraCustom doesn't require tmodloader, but it will load installed tmodloader mods if they are present. (This may have the side effect of making a ModLoader folder in your Save directory even if you don't use tmodloader, but that's it. It's not a problem.)Does this mod require you to download terrariaModloader? Reason why I'am saying this is because there is a tModloader folder despite not downloading it. I only downloaded TerraCustom.
If you use TerraCustom to generate a world larger than "Large", then you have to use tModLoader and Large World Enabler since vanilla Terraria can't load them.