How to install Xposed on S6
It's exactly the same for me. Except my device do not want to boot in recovery mode. How did you do this? Because I'm stuck on the black screen and blue LED.

Edit: There was an issue and I needed to flash again TWRP with Odin and sideload  Xposed uninstaller.

Edit 2: Solution
As it say on xda forum "Bootloops on Samsung stock ROMs. That's due to Samsung's changes to ART. There are unofficial builds that work around this by deodexing and adjusting the ROM." So we need a deodexed rom: XtreStoLite 3.3.1 FINAL Marshmallow Android 6.0.1 for example. Still, Xposed will no work because the official version do not support Samsung S6. There is an unoficial version for S6 here. It worked for me.