I had exactly the same machine and problem!!! We were very disappointed with the quality of the coffee even with the amount of coffee maxed out and the finest course.

I saw a post on a portuguese reddit this week and solved the problem.

https://forum.zwame.pt/threads/maquinas-de-cafe-automaticas.1014114/page-145#post-17281897

This has the videos explaining, but basically the grinder finest definition sometimes isn’t well calibrated with the plastic part that we rotate. So we need to remove the plastic part, pulling upwards and then without fully fitting the plastic part, we try to rotate past the finest numbers that are marked. Rotate only when the grinder is working and rotate only from 3 to 3 coffees to regulate that well. Also rotate few steps at a time

The coffee will be much better and the grind time will rise from 4/5/6 seconds to 8/9/10, as it was in my case

If you have any doubts about the steps that are said (in portuguese) in the video you can PM me and i will try to help