1. Open iLOQ S50 App
2. Press the lock symbol in the middle to activate your mobile key
   
3. Place your phone on the lock, top corner against the knob
4. Keep it still - don't move and wait few seconds
5. Now the lock is activated and you can turn the knob

Note: Depending on your iPhone, the NFC antenna is typically locates in the top / top corner. 
It is also important that the antenna area of your iPhone touches the knob of the lock and you don't move the phone during the opening process.

If you need to re-open the lock, remember to press the lock symbol to activate the app first.  

Quick user guide, iPhone: