If your browser isn't set to open safe downloaded files, double-click the ZIP file to decompress it. You will see a disk image file.
Double-click the disk image to open it.
Drag and drop the application from the disk image to the Applications folder shortcut.
After the application has copied, press ⌘︎E to eject the disk image.
macOS Privacy Options
With continued changes in Apple's security policies, you are now required to explicitly grant permissions for many actions your applications perform. Regarding DEVONthink, here are options you always should allow in macOS' System Settings > Privacy & Security, noting these allowances already had been granted for years preceding Apple's changes:
Full Disk Access: Provides access to the filesystem, including your Desktop, Documents, Downloads, mounted volumes, items in your user Library, as well as Safari bookmarks and history.
Automation: Several features in DEVONthink interact with other applications, including the Finder. Press Allow when prompted "DEVONthink want to control application X"
Local Network: Starting with macOS Sequoia, you need to give DEVONthink access to devices on your local network, e.g., a multifunction scanner/printer. This is also required for syncing to devices on your network, e.g., via Bonjour or local WebDAV services.
Contacts: Provides access to your Contacts, used when importing contacts or handling emails.
Some of the features of the Sorter require specific permissions. Enable DEVONthink for these settings:
Accessibility: To use the Copy Selection function.
Screen & System Audio Recording: To use the Screen Capture function.
Camera: To use the Video Note function.
Microphone: To use the Audio Note function.
Licensing
Now that you've got DEVONthink installed and given it permissions, you want to activate your license on this Mac. A purchase or upgrade comes with two seats so you can install on two Macs, say a desktop and a laptop. Do this on each Mac for which you want to use a seat….
If you need to manually update the software, follow the previous installation instructions, but allow the Finder to overwrite the old version. Your database(s) will not be affected. To avoid any potential problems, do not use a third-party uninstaller utility. Just replace the current version, as directed.
Uninstalling
If for some reason you need to fully uninstall DEVONthink from your Mac, trash the following files and folders (~ stands for your account's home folder):
