To fly in controlled airspace with DJI products you always need to get permission and unlock through DJI Fly Safe first – even if using other software like Litchi for the actual flight operation. You can obtain permission by following the steps detailed at this site: Fly Safe - DJI. When very close to airports, heliports, military bases, national borders or prisons, you may have to upload clearance documents from your country’s aviation authority or Air Traffic Control agency in order to unlock the drone.
Even if DJI GO, DJI GO 4 or DJI Fly are NOT going to be used in your flight operation, you have to start with your DJI app in order to unlock the controlled airspace. This will load the data on to your drone. Afterwards, close down your DJI app and boot up Litchi or any other apps you use.
It is a bit of a bumpy procedure, and not particularly well explained on the DJI site, but once you get the hang of the process it does work smoothly.