Hi @jackluo923,
Thanks for joining the Community!
Since you only need to make this request once to update the New Universal Login settings for your tenant, you can use the Management API Explorer.
In your dashboard, go to APIs and select “Auth0 Management API”. Go to the API Explorer tab and authorize the explorer if needed. The token can be copied from this tab:
You can then make the request with cURL or adjust for Postman, etc using the Access Token:
curl --request PUT \
--url 'https://YOUR_DOMAIN/api/v2/prompts/login/custom-text/en' \
--header 'authorization: Bearer MGMT_API_ACCESS_TOKEN' \
--header 'content-type: application/json' \
--data '{ "login": { "description": "Welcome to ACME'\''s Website" } }'