Follow all the instructions to get to F.17.
Once you are on F.17, your device should be an LE2125.
Once on F.17 you *should* be able to flash to 13.1 using Magisk Modules / Install From Storage.
After flashing 13.1 DO NOT REBOOT YET.
Flash Magisk Install / Install to Inactive Slot (after OTA) THEN REBOOT, to keep Magisk Root.
After the reboot use Magisk Modules / Install From Storage, to install TWRP to recovery (if you want to have TWRP as your Recovery) then you should be golden....
IIRC, this procedure *should* work.