Can't install TWRP on Galaxy A3 (2017)

I want to root my phone, but first I was trying to install TWRP. The phone is Galaxy A3 SM-A320FL (2017). (Edit: System is Android 7.0) What I did: - Turned on OEM-unlock and USB-debugging on the phone - Installed the Samsung USB drivers on my laptop - Turned off phone, went into "Download Mode" by pressing Volume down - Home - Power - Started Odin. Connected the phone. In Options I ticked only "Auto Reboot" and "F Reset Time" - Clicked on AP and selected the TWRP file and hit Start - Then PASS was flashing in Odin and the phone rebooted immediately. - Turned it off and tried to enter recovery mode. (I think I did it with Volume Up - Home - Power) ...and then a blue screen came and said "Installing system update". After a while it changed to a blue screen that said "No command". Then after a while it changed to a screen that I think is the standard recovery tool. So no TWRP. I hit Reboot and the phone rebooted normally. Then tried to do the whole thing again with a different TWRP file but it went exactly the same. I'm newbie with all this so I might be using a wrong TWRP file or something, I also seen tutorials where it says dont thick Auto-Reboot and they press all sorts of button combinations. I don't want to brick this phone so I wanted to ask how to do this right before I try it again. Thanks for help!