Hello,
Unfortunately, onbox (ASDM managed) FirePower is not capable of generating reports. This is a limitation of running onbox FirePower. I have not heard of anything, on the roadmap, to add this functionality.
Another limitation, of the onbox FirePower deployment, is you're only able to view detailed events in real time, through Monitoring > ASA FirePOWER Monitoring > Real Time Eventing, there is no way to view detailed historical events. With that said, you can view historical data by going to Home > ASA FirePOWER Reporting tab, then to the specific subcategory, but this only shows you limited data.
If you require/need these features, you'll have to invest in FMC.
Regards,
Barrett