"enable debugging" is to activate adb on the phone.
ADB is not needed if you do the vol down hold -> power on trick to boot into bootloader/fastboot on the phone.

ADB can be ignored and just adds confusion.
If you read the instructions from sites like i linked, they only use ADB to enter bootloader to not make the user miss the finger combo i guess...
ADB generally is a kind of shell running on android you connect from your phone to. You can do things like copy files to and from the device and reboot it as done here. But setting up adb and confusing modes is what fails for most users so i would advise to ignore adb.

1. install sony usb windows driver (i guess. maybe only for adb but may be needed for fastboot permissions?)
2. "finger" the phone into bootloader/fastboot mode
3. extract linked fastboot zip to pc
4. from extracted folder issue fastboot commands