To authenticate with Avalara (Sandbox), you will need:
User Name - The User Name associated with your Avalara (Sandbox) AvaTax account, used to authenticate API requests. Alternatively, you can use your AccountID instead of a User Name.
Password - The password linked to your Avalara (Sandbox) AvaTax account, required for secure authentication. Alternatively, you can use your License Key instead of a Password.
AvalaraClient - A key that can help you diagnose and resolve issues with your software.
This guide will walk you through finding or generating the Account ID/License Key pair within Avalara (Sandbox).
You can use your username/password pair for authentication, or alternatively, opt for the Account ID/License Key pair. To obtain the later credentials, log in to your Avalara dashboard.
Navigate to Settings and select License and API Keys to obtain both the Account ID and the License Key. Under the License Keys tab, click on Generate New Keys to create new credentials.