Ok I understand.
First try to ping ntfy server for Unraid in console and see if it is visible
then try to post message from console (replace token and url)
curl \ -H "Authorization: Bearer tk_AgQdq7mVBoFD37zQVN29RhuMzNIz2" \ -d "Look ma, with auth" \ https://ntfy.example.com/mysecrets
https://docs.ntfy.sh/publish/#access-tokens