I’m working on integrating a report into a browser, and I get this error:
An error has occurred during report processing. (rsProcessingAborted)
Cannot create a connection to data source ‘dsFederatedSample_SurveyLevel_STG’. (rsErrorOpeningConnection)
For more information about this error navigate to the report server on the local server machine, or enable remote errors

Does this have to do with SQL vs Windows authentication?
First thing I would try is to get a bit more information on the error – that’s a pretty generic message.
You could enable remote errors as per the error message and replicate the error for more information.
Or check the Report Server error logs to see what error was logged.
The next step would be to connect as the Data Source user to the database, run any code/stored procedures that the report is using with the same parameters you’re using when running the report, and see if any errors occur. Make sure the account you are using has permission and that you have entered the name and password correctly in the Data Source.