In order to continue installing macOS Catalina, you need to log in as an administrator. Install macOS Catalina is trying to add a new helper tool

I'm trying to install macOS Catalina. I have downloaded the update, but when I click the "install" button, my iMac pops up a window saying "In order to continue installing macOS Catalina, you need to log in as an administrator. Install macOS Catalina is trying to add a new helper tool."

I have entered my Admin User Name and password (and in fact, I'm logged in as the admin and have logged out of all of the user accounts on the machine), but after I enter the Admin User Name and password and click the "Add helper" button, my iMac does nothing except close the window telling me that the helper tool needs to be installed. If I click the "install" button again on the "Install macOS Catalina" window, my iMac once again pops up the same message telling me that macOS Catalina needs to install a new helper tool. I have gone through this complete and utter waste of time 5 times and still nothing happens after I click the "add helper" button.

How do I get past this annoying roadblock?

I have attached a screenshot (removing my admin user name and password for the screenshot).