@javier Thank you for your query!!!
As mentioned in this article can you please check below:
Message: Cannot access user batch account; please check batch account settings.
Cause: Incorrect Batch access key or pool name.
Recommendation: Verify the pool name and the Batch access key in the linked service
Also make sure your Batch URL is correct and uses your Batch account.
Hope it helps!!!
Please 'Accept as answer' if it helped, so that it can help others in the community looking for help on similar topics