Download at least every 28 days. An operator should be on top of it and be able to see who has and hasn’t downloaded recently (but you may not be on the radar because there may be no record of you until you download for the first time). Agency workers may be asked to download more often (like every day) because it is always possible that they may never return for whatever reason.
I wouldn’t worry because the operator should have shown you where to download, whether it requires handing your card over to someone or if you can do it self-service.
The operator may run into trouble come an audit because there are also vehicle downloads that require to be done so it would probably flag up as missing data. I really don’t think it would come back to bite the driver to be honest, as the operator would have had plenty of time to request a download.