You might see this error message if you try to install an older version of Google Ads Editor after having installed and then uninstalled a newer version.
To resolve this issue, choose one of the following options:
Option 1 (try this first):
Open Terminal, then type the following, where n.n.n is the number of the newer Google Ads Editor version that you installed and then uninstalled:
cd /Library/Receipts
rm -rf Google Ads-Editor-n.n.n.pkg
Now try installing the older version again.
Option 2 (if option 1 doesn't work):
You'll need su privileges for this option. Open Terminal, then type the following:
sudo pkgutil --forget com.google.adwordseditor
Now try installing the older version again.