I’m trying to figure out if it’s possible (via AppleScript) to fill out a server authentication dialog box asking for username and password (using Google Chrome).
This is the dialog box I see when visiting the URL I’m working with:

I can script a regular form, but since this is coming prior to page load, I can’t use inspector to target these specific fields.
I do this all the time and my strategy is simple: Replicate the keystrokes that you would normally use to fill in the information. You can’t use the mouse. Usually it is a matter of tabbing to get to the correct field, entering the information, tabbing to the second field, entering that information and typing a return. The following gives you an idea from a script I use to open a secure website:
tell application "plugin-container"
activate
open location "https://the.url/"
delay 1
tell application "System Events"
keystroke "userid" & tab & "password" & return
end tell
end tell
Hope this helps!

Is there not a way to mount a volume with password embedded so that the dialog box is by-passed?