Welcome to the forum — and Dorico, @double8range. If you continue to make use of the forum, you will come to find that it’s filled with many knowledgable users including members of the Dorico team itself. (Incidentally, many of us are also highly capable musicians, even including pianists and other keyboard performers in our midst.)
If you pause for a moment to ask whether any commercial software on the market (for eight years, as it happens) could possibly not offer basic MIDI keyboard input, the obvious answer might lead you towards greater curiosity, search effort, and a default position of giving the software (and its developers!) the benefit of the doubt.
As it turns out, Dorico actually has input features that are quite powerful, including the ability to extend the note input caret across multiple staves and enter chords that are intelligently distributed across them. (Incidentally, if you ever are inputting with your computer keyboard instead, typing Q engages/disengages Chord mode, so you needn’t mouse-click the tool if you prefer not to.)
Speaking as someone who used Finale for 32 years before switching to Dorico, I sympathize with the disorientation that comes with the new UI. But with a bit of time and effort in studying, I’m confident you’ll find lots of high-level functionality and features.
Regarding your specific issue:
Here’s a very brief (2:10) video from Dorico’s YouTube channel about note input:
…which is a part of this note-input overview series:
I think you’ll find these to be really helpful.
Good wishes to you as you dive in.