Welcome to Microsoft Q&A platform and thanks for posting your question here.
It seems that the error message "Cannot find the CREDENTIAL 'https://.dfs.core.windows.net/dataverse/deltalake/dimensionfocusbalance_partitioned', because it does not exist or you do not have permission" is related to the credentials required to access the Delta Lake storage where the data for the view is stored.
When you connected to the view through PowerBI with your AAD user ID, it worked because your user account has the necessary permissions to access the Delta Lake storage. When the business user tried to connect using the SQL user account that you created, they did not have the necessary permissions to access the Delta Lake storage, which resulted in the error message.
To grant the business user access to the view without giving them access to the entire data lake storage or the Synapse workspace, you can create a shared access signature (SAS) token with read access to the specific Delta Lake folder that contains the data required for the view. You can then provide this SAS token to the business user to access the data.
Once you have generated the SAS token, you can provide it to the business user to access the data required for the view. The user can then connect to the view in the Synapse serverless SQL pool database using PowerBI and the SAS token.
Reference
https://learn.microsoft.com/en-us/azure/storage/blobs/assign-azure-role-data-access?tabs=portal
I hope this information helps you. Let me know if you have any further questions or concerns.