How do I import CSV files onto my Iphone?

Hello,

I recently started using an app called 'Intelli' - it is a flash card learning app. In the description is says it is possible to import CSV files via Itunes into the app - so I don't have to type every question on the phone but I can do it in an excel/ numbers sheet, save as in CSV format and get in on the phone via Itunes. However, I am not sure how to do this - I tried to import the CSV sheet into Itunes (it does let me choose to import it, but it does not show up in Itunes), I tried it via contacts (this seems the most common use of CSV files and every article I found to answer my question eventually ended up talking about contacts) when I connect my phone to the Macbook, but no luck. Has anyone on this platform successfully saved CSV files on your Iphone via Itunes?

I'd be grateful for some help with this!

Thanks,

AmelieMac