Install Add-ons: Operation not permitted

Hello. When installing the latest DTproOffice2-0pb5, on trying to install the Add-ons, I get: “Operation could not be completed. Operation not permitted. Please try to fix the problem and try again using the Help > Install Add.ons menu command.” I’d sure like to fix the problem, but how? It’s about my home folder, and I am logged in as administrator. What permission is lacking here?
Thanks

Probably a Sharing & Permissions error in one or more of the folders into which DEVONthink Pro Office tried to write information.

DTPO2’s Install Add-ons installs files into four areas of your user library; Application Support, Mail, PDF Services and Scripts. You should have read & write permissions for those folders (and relevant subfolders), else the installation will not be allowed.

To check for Sharing & Permissions errors, select those folders in your /Home/Library/ directory one at a time. Open the Info panel of the selected folder and examine permissions under Sharing & Permissions.

If the Info panel indicates that you do not have read & write access, you can correct the error by clicking on the ‘Lock’ icon. Enter your administrative password, then correct the permissions to show that you have read * write permissions.

When finished, choose Help > Install Add-ons and confirm installation of the checked items.