Hi Carsten,
Thanks for writing in !
Firstly, please ensure that the Sentinel Master key is compatible to be used with EMS.
To confirm, kindly share the color and firmware version of the Master key. It appears under 'Version' detail on Sentinel Keys page of Admin Control Center (http://localhost:1947/_int_/devices.html).
In case its compatible, you may go ahead and introduce it on EMS machine. It does not affect working of Business Studio Server.
Thank you,
Gaurav Bhanot