Which folder Android File Transfer app directly get into?

[AC Question]

I want to root my phone (Nexus 5X MMB29Q) currently and I figured that I need to put the SuperSU file into the sdcard folder by using computer instead of directly downloading the zip file online using my phone which will be ended up showing under the Download folder. The reason for doing that I guess is because my phone is encrypted by LG or Google so I cannot get access to my downloaded file in TWRP if I don't know the password which is obviously unbeknownst to me. So I downloaded Android File Transfer, but I didn't see the sdcard folder there. So I'm wondering if the folder IS the sdcard folder when I opened Android File Transfer (the one that it showed us directly when you open the software) because I saw the Download folder was there. And also I'm still not sure if I can find the SuperSU file even though I put it under the sdcard folder but without knowing the password to my device.

Hope someone can help me with rooting my Nexus 5X thx!!!!!!
Last time I didn't root my phone successfully because of that so I flashed back to factory image again.

THANKS!!!!!!

 

[Jerry Hildenbrand]

The window that opens is the /sdcard directory. You put the zip file in the right place as long as you didn't stick it inside another folder and forget which one.