Bruce is correct in noting that conformity with styles prescriptions is ultimately the responsibility of the author. We do our best to make the process as simple and error-free as possible, but can never guarantee this, so always double-check if you are being graded on the minutiae of your citation style.
Discrepancies between the style guide and the output generally come from one of two sources: (1) problems with the metadata, or (2) style requirements which are difficult or implausible to automate. For the latter, see: APA style incorrect.
The problems you describe w.r.t. leaving out commas and authors, however, sound like they could result from submitting the unformatted blue placeholders. For the placeholders, we use our own chicago-esque style which shows only one or two authors and does not place a comma before the date, like so:
The citations must be formatted for the selected style to be applied. Once this is done, these particular references will appear like so:
The formatting process also inserts/updates the bibliogrphy in the document. For more information, please see here: https://paperpile.com/help#guide-gdocs
If the problems you encountered are something else, please provide more details so we can investigate/fix the error.