Update clickup.mdx

Co-authored-by: Mateo Torres <mateo@arcade.dev>

Author: jottakka

pages/home/auth-providers/clickup.mdx

@@ -14,7 +14,9 @@ This auth provider is used by:
 - Or, your [custom tools](#using-clickup-auth-in-custom-tools) that need to call ClickUp APIs
 
 ## Configuring ClickUp auth
-
+<Note>
+  When using your own app credentials, make sure you configure your project to use a [custom user verifier](/home/auth/secure-auth-production#build-a-custom-user-verifier). Without this, your end-users will not be able to use your app or agent in production.
+</Note>
 In a production environment, you will most likely want to use your own ClickUp app credentials. This way, your users will see your application's name requesting permission.
 
 You can use your own ClickUp credentials in both the Arcade Cloud and in a [self-hosted Arcade Engine](/home/local-deployment/install/local) instance.