▪To use picker hotkeys in animator mode:

Since MG-Picker Studio v1.6, picker hotkeys for animator mode are reduced to minimum set.
Most of time, you are just using maya hotkeys. In order to use picker hotkey, you must make sure picker window is currently actived, and your mouse cursor is within the picker area.
So quick work-flow to use a picker hotkey in animator mode, is MMB activate a picker view, keep mouse cursor within it, and then press the picker hotkey.

F7 and F8 are exceptions since F7 are global hotkey that always work, and F8 will works as long as you have picker window currently activated.
For designer mode, you have not access to maya hotkey, as long as picker window is currently activated.

▪To checkout hotkeys for animator UI mode:

Click on the top right more feature button, select "Hotkey Outliner..";

The feature was actually made using a picker file :)