Apply settings level plugin in kotlin

Help/Discuss
1

Hello
I have create a small settings plugin that configures the build cache.
How can I apply it to my settings.gradle.kts?

Here is the code of my plugin:

class JvmSettingsPlugin : Plugin<Settings> {
    override fun apply(settings: Settings) {
        configureBuildCache(settings)
    }

    private fun configureBuildCache(settings: Settings) {
        val isCI = settings.getExtra("CI")!!.toBoolean()
        settings.buildCache { config ->
            config.local { directoryBuildCache ->
                directoryBuildCache.isEnabled = !isCI
                directoryBuildCache.isPush = true
                directoryBuildCache.removeUnusedEntriesAfterDays = 2
            }
            config.remote(HttpBuildCache::class.java, Action<HttpBuildCache> { buildCache ->
                buildCache.isEnabled = true
                buildCache.isPush = isCI
                buildCache.url = URI(
                    "${settings.getExtra("ARTIFACTORY_URL")}/gradle-build-caches/${settings.rootProject.name}/"
                )
                buildCache.credentials { credentials ->
                    credentials.username = settings.getExtra("ARTIFACTORY_USERNAME")
                    credentials.password = settings.getExtra("ARTIFACTORY_PASSWORD")
                }
            })
        }
    }

    private fun Settings.getExtra(key: String) =
        this.extensions.extraProperties.get(key)?.toString()
}

I package it like this:

gradlePlugin {
    plugins {
....
        val settingsPlugin by plugins.creating {
            id = "de.tech.gradle.plugins.settings"
            implementationClass = "de.tech.gradle.plugins.JvmSettingsPlugin"
        }
    }
}

When I try to apply it from my settings script it says not found, even if I add it in pluginManagement > plugins block.