401 unauthorised issue from test connection in admin

[RajeswariMK]

Hi all,

I am using this gem with Solidus 2.10.0 and configured with the Avatax trial account. Below are the app details.
Rails version: 5.2.4
Ruby version: 2.6.0

Once it is configured, from the admin portal of Solidus, whenever I try to check the "Test Connection", it is always showing the below error.

Also, I am not getting the sales tax value while doing the checkout. ANy thoughts, what could be the issue or share your thoughts.