On Windows, you can simply install and run the Flashtool using its .exe file, but things aren’t really that easy on Linux. You need to make sure that you have the right working USB drivers ‘libusb-dev’ installed, make sure flash_tool.sh is executable before running it.
And then some more. Like, creating a persistent rule. You might still get an error or two but thankfully, user Miss Montage has written a pretty explanatory guide (find here) for all of this. Find the guide here, and should you run into a problem, be sure to ask out at that page, or ask us using comments section below.