g920a root

need write g920a cert file but asked root i av tried to get it without sucess

BACKUP INSTRUCTIONS:
Phone must be rooted!
If the software can’t root the phone automatically,
then you must root your device manually.
1. Power on the phone.
2. Tap 7 times on ‘Build number’ in ‘Settings’-‘About phone’ to enable ‘Developer options’,
go to ‘Settings’-‘Developer options’ and enable ‘USB debugging’.
3. Connect the phone to PC with USB cable, install drivers if needed.
4. Select device in ADB settings.
5. Press ‘Read EFS’ button to read backup or ‘Write EFS’ to restore.
6. Press ‘Read CERT’ button to read certificates or ‘Write CERT’ to restore.
7. Press ‘Write NV DATA’ if you need to restore NV backup.

Operation: Write CERT
Selected model: SM-G920A
Software version: 27.0

Waiting ADB device… ok
Reading phone info…
Model: SAMSUNG-SM-G920A
Android version: 6.0.1
Product code: SM2G920AZDAATT
Phone version: G920AUCU3CPD6
PDA version: G920AUCU3CPD6
CSC version: G920AATT3CPD6
CSC country code: USA
CSC sales code: ATT
HW version: REV1.0
Phone SN: R38G60FDS6D
Chip name: EXYNOS7420
Modem board: SHANNON333
RF cal date: 20150612
IMEI:
Checking Super user right… false
Root your phone manually and then repeat

Done with Samsung Tool PRO v.27.0