You’ll want to choose “Yes” (I already have a Sync Key) after access Sync > Setup Sync Key for either of these options.
How, with Step by Step, How do I get my data into Codebook on my Macbookpro?
I do not and will never use google anything.
I do not use Dropbox (Is this the ONLY way to “copy” “transfer” my data to my Macbookpro?)
Desktop WiFi sync is only available for syncing between a mobile and Desktop/laptop device, so you won’t be able to sync directly between two macs using Desktop WiFi sync (without Codebook on a mobile device).
If you’d prefer not to use Google Drive or Dropbox sync, and don’t want to use Codebook on a mobile device, one other option is to sync via Local Folder sync on a shared network location. This would allow you to sync between your two Macs to the mounted network location without using Dropbox/Google Drive. Apple has some general instructions here for File sharing: Set up file sharing on Mac - Apple Support (make sure to select your macOS version at the top of that page if your new machine is something different from Mojave) which you should be able to use to share a folder between your Macs.
Here are some steps for sharing a folder between your Macs on the same network:
On your Mac Mini, create a new folder on your Desktop and call it Codebook-Sync
Go to Apple menu > System Preferences and select Sharing.
Check the checkbook next to File Sharing on the left hand panel, then click the + button (in the center pane) to add the Codebook-Sync folder you just created to the Shared Folders list. Leave that Window open on your Mac mini
On your new Mac, open Finder and access Go menu > Connect to server. Enter the network location from the File Sharing window on your Mac Mini (will start with smb:// or afp://), then connect. You will be prompted to login as a registered user to connect. Use the user credentials the you use to login to your Mac mini, then click connect.
Within Codebook on your Mac Mini, go to Codebook menu > Preferences > Sync Tab and select Local Folder Sync, then select Choose Folder and select the shared Codebook-Sync folder on your Desktop.
Perform the Sync from your Mac mini.
Within Codebook on your new Mac, go to Codebook menu > Preferences > Sync Tab, and select Local Folder Sync then select Choose Folder and select the shared mounted Codebook-Sync folder (/Volumes/Codebook-Sync)
Let me know if that allows you to use Local Folder sync using a shared folder to Sync between your two Macs. I’ll be happy to help if you have any questions or run into any issues along the way. Thanks!