So, I knew it wouldn´t be that easy to install the beta on an Meizu Metal with Shop ROM. What worked was to copy the update.zip file to the root of the phone directory and then turn off the phone. Reboot with VOL UP and POWER BUTTON and then install the update via recovery.
The Shop ROM didn´t even have an update app…
Does anyone know if it´s possible to activate GERMAN as a language with this beta ROM?