This is best asked of the Server Admin folks.
Instead of a ? in front of the second parameter, you should use a &.
The ? designates a change from the url to the parameters. Additional parameters are separated by an &.
tabcmd get "/views/Reporting/xyzDshBrd.pdf?Customer=ABC&State=Arizona" -f "C:\Report_Output\xyzDshBrd.pdf" --timeout 60