Cinema HD - download limit?

I have installed Cinema HD on my Firestick 4kMax. There seems to be a warning message that the storage for downlaoding is limited to 1.3gig. This happens to be the free storage on the firestick. I have a USB stick, which I have setup to have mixed storage between the firestick internal and normal external storage. Internal is around 12gig. Cinema HD is installed on the USB.
My questions are:

  1. I can’t see the USB internal storage on a file manager (x-plore) so if I download a file greater than 1.3gig, will the file get saved/downloaded
  2. Why can’t I see the USB internal storage and is there a way to see it