I’m not 100% sure because I’m not using Windows and can’t check how it’s supposed to look.
But in your case it’s shown as “Android ADB Interface” while the HOWTO mentions “Android Bootloader Interface”.
So if I interpret that correctly, your phone is in the wrong mode. When adb commands work, fastboot commands don’t and vice versa.
I don’t know enough about Samsung devices but maybe you can find some useful hints in this topic: Know your hardware - Samsung
Probably the “Your first boot into TWRP” section contains what you need.