Sonoma won't open Wacom installer dmg file

I use a Wacom tablet-or, at least, I did until I upgraded to Sonoma, at which point everything stopped. I tried downloading a new driver for the tablet, and Wacom has one that would work, but my Mac, running Sonoma, "Refused permission" to open the .dmg, thus refusing to install the Wacom driver. What the heck is going on here?