1. Plug your USB into the tablet or the hub (the black plastic box behind the tablet)
2. A notification should pop up that registers your USB. Swipe down from the top to access the notifications and tap "set up" and "use as portable storage", then swipe down from the top again and tap "explore". If a different notification appears, or you accidentally dismiss it (you can't see it anymore), go directly to a file explorer (File Go, Files, File Explorer, etc.) and find it through browsing that.
3. Select the files you want to copy (usually by pressing and holding a file, or going to the 3 dots in the top right and pressing 'Select All' to select an entire folder).
4. Go to the top right 3 vertically stacked dots and tap that to bring up a menu to "Copy To".
5. Go to your home directory and tap the SD_card (or internal) directory/folder, then tap the "Download" directory.
That's it! It should copy all the pattern files to your tablet's local Download directory. Now you can go into the Perfect Stitch app to the import tab on the layout screen, then tap 'Import File' or 'Import Folder' to use the file browser to navigate to the Download folder to import the patterns. See Import Patterns into Perfect Stitch for more details about importing into the Perfect Stitch app.