Hi,
For 2018, you need to go to the player settings in the XR settings and download/install the Vuforia Support installer.
On MAC: Warning, this doesn't work inside the Hub, you need to move the unity application folder at the root of the Application folder, name the folder Unity, install vuforia packager, and the you can move it back inside the hub..
So, yeah, not really recommended...
for 2019, the 2017 support package will work if you simply delete the offending actions, they are obsolete. I will issue a new version early next week for 2019 so that you can get a clean install.
Bye,
Jean