Do not right-click, and do not command-click Run as an Administrator
Follow the instructions in the install wizard.
If you’re asked for an administrative username and password, enter them or contact your administrator to sign in.
If you’re not asked for an administrative username and password, you’re already an admin on your computer.
Complete the installation and sign in to Dropbox.
Smart Sync and admin privileges
Some Dropbox users will have access to Smart Sync. If you have access to this feature, check that Dropbox is installed with admin privileges on each computer where the feature will be used.
If you’re the admin on a Dropbox Business team, you can see which team members installed Dropbox with admin privileges. However, you can only do this before you enable Smart Sync. Depending on the policies at your company, your team members may be able to install Dropbox with admin privileges on their own. If not, they may need the assistance of your IT team.
Why does the Dropbox desktop app for macOS require Keychain access?
Keychain is a password management system for Apple's macOS. Dropbox requires access to your Keychain to help verify your account and to provide another layer of security over the Dropbox app settings.
To grant Keychain access to Dropbox, click Allow or Always Allow (recommended for seamless access) when prompted to do so from macOS.
Clicking Deny will result in a "Couldn't start Dropbox" error message. For security reasons, Dropbox will not start without access to your Keychain.
What is the Dropbox Web Helper for macOS?
Dropbox Web Helper supports the Dropbox user interface on macOS computers. It only runs when the desktop app is running. Dropbox Web Helper is an independent process, so it may start and stop at different times than the desktop app. If you adjust your firewall or antivirus software for Dropbox, we recommend similar adjustments for Dropbox Web Helper.