Importing invoices from Zoho Invoice

How can I access the storage/logs/ to check?

Do you have any csv template I could use for importing invoices? Maybe this would help to minimize errors. I have tried to import over client contacts and products and they worked fine. Only the importing of invoices is having problems.

I have another question. If I import over an invoice with new products or clients that’s not already saved, would the system automatically create a new record for the client and/or product, or would I still need to create them manually?