If you haven't issued a transfer code you can copy the data file that can be found at these save locations.
Save Locations:
[NA] Storage/Android/data/com.aniplex.fategrandorder.en/files/data
[JP] Storage/Android/data/com.aniplex.fategrandorder/files/data
You will have to copy these specific files and put it at the same location in your target device or emulator.
They start with:
Open up the game and it will show your friend ID on the bottom if you done it correctly.
P.S if you want to read this again and forgot what it was. You can bookmark this specific comment. Thanks!