Help needed to flash Sony Xperia XZ Premium

[NameUserIII]

Hello,
I played with custom roms and accidentally wiped internal storage. The phone is stuck in boot (then turned on at first it is showing that boot-loader is unlocked then sony logo and again boot-loader, Sony logo...
TWRP not launching as well - it gets stuck with twrp's first image on boot).
Now I am trying to flash it with firmware, but I am running in to many problems. I do not know witch driver to instal for Sony experia xz premium (I just installed Flashmode and Fastboot drivers). I installed Sony driver (https://developer.sony.com/file/download/xperia-xz-premium-driver/), but when the phone is connected to the computer in device manager it is not using the driver and I could not figure it out how to force it to use the driver (maybe because the driver is old - made for windows XP).
Also in Flashtool when I try to enable log in debuging mode the program crashes and I need to reinstall it to be able to run it.
Please help :)