Boox Note add fonts - a newbie question

I have searched the internet and found a Youtube video that says how to add fonts to a Boox Note but it's in Chinese - not helpful to me.

Anyway, I'm looking to add some fonts and found this in the manual:

11.5 How to add fonts
Users can download fonts online, then copy the fonts to the folder /fonts; Users can select the installed fonts when reading.

My question is simple - where the heck is the /fonts folder?

Also, can I sideload fonts if I ever find that folder? I imagine yes, but.....

Thank you.