Volumio App fails with Star Pure DSD DAC

My new Star Pure DSD Dac has an internal Raspberry PI with preinstalled Volumio. They say it’s easy to use Volumio, but I failed. If you turn on the DAC and you do not connect with CD Player or computer the internal PI is sending a WIFI Signal called Volumio. Now you can connect an external HD via USB or a NAS drive via Ethernet with the DAC to play music files. I connected the HD and downloaded Volumio App on apple ipone or ipad. I connected the iphone/ipad to the ”Volumio” WIFI the PI is sending, what was successful. When I open the volumio app “setting" ask for IP adress. I think the IP adress of PI WIFI is meant, what I put into settings. Then a ball is turning, but nothing happens, no error message, nothing. Can anybody help me?