Are you pushing the portafilter into the plastic grinding cradle as shown in the photo on page 8 of the “Getting to know your machine “ side of the instruction book?
I find it a good fit and little coffee is wasted. Pushing the portafilter starts the grinder motor.
If you hold the portafilter under the grinding cradle coffee will go everywhere.
I use the single walled, single dose basket.
I warm up the portafilter and cup before adding the coffee by running a shot of water.
I set the grinder doser on single with the knob at about one oclock.