[Galaxy Tab S2 Q&A, Help & Troubleshooting] tkongx0:
Tab S2 SM-817A (AT&T version)

After reading a bunch of things online and this forum I got mine to bypass FRP. Remind you my model is: Tab S2 SM-817A (AT&T). Mine was stuck at the "enter a valid email address that was used on this device" and I could not get over it. I first tried to push the stock Android 5.1.1 back into the device via Odin, thinking this might solve the issue but it didn't. A reset through samsung's boot up option (holding power button + up volume + power) didn't work either.

I then read from this forum to try the "hotspot" trick. I connected my tab to my hotspot (during setup). When the screen switches to "Software update", I turn off my hotspot so it doesn't verify and give you a prompt about not being able to connect (or something similar) but I was able to hit the "Next" at the bottom right. This allowed me to create a User and a PIN. I made the PIN and then it went back to the main setup page. I screen locked my device and it came up with the PIN screen to unlock. At this point I saw the camera icon at the bottom right, which I swiped up to get into. I took a picture and click at the bottom right to get into that picture and chose the "share" option. I click on the gmail icon (to pretend to share the picture) and this got me to the option of setting up an email. Don't use the gmail option as it'll ask you again to only put a valid email that has been used on the device previously. I chose the other option to setup a different email account (in my case, hotmail). I was able to set that up and then it took me to a screen which look like the "compose email". At the top right there was an "..." option which had "manage users" and once you click on that you'll get into the android settings. From there I was able to attempt a reset within the android settings. I did that thinking it'll get over the FRP once I set it up again and it turns out that wasn't the case. I was still stuck.

So I went through the process above all over but once I got into the android settings, I went to the Users section to create a new user. Once I did that it allowed me to log into that user and I was at the normal android home screen with all the apps available. At this point I could even setup a google account to tie it into the device. So at this point I thought to myself that having 2 users was pointless and I only wanted to setup one user. *Unfortunately you cannot delete the 1st user (when you do the hotspot trick to setup that user). I then downloaded FRP Bypass APK and installed ES File Manager. I went through ES File Manager to install FRP Bypass and when you actually open the App, you have to click at the top right "..." and use the browser option of logging into your gmail. I did that and it went through a process which looked to unlock the device (can't find the correct term).

I then did another reset within the android settings to wipe out the device completely. This time when I went to setup the device it was like brand new. It did not stop me at the "enter a valid email address that was used on this device"..

Hopefully this method helps someone else. Just wanted to share the good news!