Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.
I understand that you are trying to make a REST call to get Azure ExpressRoute Circuit.
I am afraid I did not get what resource you are trying to "GET"
For ExR Circuits, the reference is,
However, I see you are doing a REST call to some other resource "dedicatedcircuit".
Can you please provide more clarity on this?