Bing instant indexing error

Hello,

I have just installed BING instant indexing (source:https://rankmath.com/blog/bing-indexing-api/)

I have set up the BING API key in Rank Math but when submitting URLs manually it shows :

Bing URL Submission API HTTP error 400: {“ErrorCode”:14,”Message”:”ERROR!!! AuthorizationFailed”}

Can you help over this?

Many thanks