Getting an API Error - Credential Issue

Hello,
My name is Moosa Nayeem. I work for TapClick's on the data integration
team. I am reaching out regarding an issue reported by one of our
mutual clients Recrue Media. The client has provided a set of creds
which they have mentioned are valid credentials confirmed by Taboola.
However, we see the API call failing for those credentials.

API Response:
RESPONSE:*
error":"invalid_client","error_description":"Bad client credentials"}

Thoughts?