Since I lack the necessary knowledge, I ask if anyone can help me set up Devonthink on my Macbook Pro and I-Mac so that both PCs collect data synchronously.
Syncing is covered in the built-in Help > Documentation > In & Out > Sync. Please review it and feel free to ask questions, if you have them.
Cheers! 
Welcome Helmut.
You can start here.
On the Mac…
“1. In DEVONthink’s Preferences > Sync enable the iCloud sync location.
2. Enter an optional encryption key, if desired.
You will use this same key on other devices running DEVONthink or DEVONthink To Go, syncing with this sync location.
Note: If this is a second Mac connecting to an active sync location. you must enter the encryption key you initially specified. If you didn’t specify an encryption key, you must leave it blank.
Also, You cannot add / modify / or remove the encryption key later, unless you clean the sync location first, so it’s best to decide and specify it when you first enable the sync location.
3. Check the checkboxes next to databases you want to sync.
Note: DTSync is done locally. After sync is finished, iCloud uploads to Apple’s servers, then to devices using your Apple ID. This means databases may not be immediately available to sync on the other devices. The initial sync requires patience…”