I had the same experience, despite adding the points from Corona subscription and using those, my first ever render was still watermarked and I had to manually add some credit (it wasn't because I was in negative, I added 180 euros from Corona, did test render for 5 euros, so I still had 175 but also watermark). I guess for complete first-timers in Rebus, it doesn't yet consider the user as customer when using promo codes only ?