just received the following answer from development team - I did not test it
"You can enable 'annotationsEnabled' in Studio's builder settings and set the 'display-annotations' feature flag in View (though I'm fairly certain this is not available on Hololens)."
can someone explain me, where exactly do I have to set this flag?
"...and set the 'display-annotations' feature flag in View..."
I edited the builder-settings.json and the creo illustrate annotations now show up in the vuforia studio preview but not at the published experience on my mobile phone (with vuforia view).