I can't apply the gradle 6.x plugin

It says I'm supposed to write:

plugins {
id "com.gradle.enterprise" version "3.5"
}

gradleEnterprise {
server = "https://gradle-enterprise.mycompany.com"
}

On the settings.gradle file according to: https://docs.gradle.com/enterprise/gradle-plugin/

But then I get an error saying:

2: Only Project build scripts can contain plugins {} blocks

from I can't apply the gradle 6.x plugin