I bought my first ever bluetti power station recently and have downloaded the app as well. I don’t have wifi at my place of residence. In order to perform a system or firmware update of the bluetti power station we have to go through the mobile app right? And we can use Bluetooth or wifi radio frequencies in order to connect to the power station? Could somebody please explain simply?
In order to update your Bluetti powerstation firmware with the Bluetti mobile app, you need a live internet connection on your phone, either via your mobile data provider or via WiFi.
You then need to log in to your Bluetti account on the phone and connect to your power station via Bluetooth. Then check for firmware updates and install them when they are available:
@sacrilegious Yes, please try to update the firmware according to the description from @TheQuickFox (provided that your BLUETTI model supports connecting to the app). Additionally, thank you for your supplementary explanation and for sharing the YouTube video. 
Is having a bluetti account for the mobile app absolutely necessary? Or can one get by without one?
You don’t need to make an account to use the basic functionality of the app. (Guest mode)
But for firmware updates you need to log in.