First, if you dont speak german and planning for midnight checkin, be in contact with the staff for introductions. Also, if you dont do well with tech, dont try it. Staff was very nice informing about the procedures how to checkin late, however they were not complete. They need to make english introductions. Another customer arrived same time with me and she didnt know how to checkin either, introductions came with app install advice, which was false tho. Outside door was locked. We managed to figure it out after logging on to their wifi, and had ro manually find an email where you did pre-checkin, now the checkin button takes you to their application to open doors in the building (in german, so we kinda opened every door we could before the front door opened).
After that, everything was fine, if not countimg their problems one day when the app didnt work so no1 was able to open any doors for few hours :) the staff kindly helped.
Place was clean. I had a suite (or what did they call it), the bed was absolutely brilliant with big pillows!
Taxi from/to airport, night time 95euros daytime 79euros (free now app said 45-65e, but they charged 79e).