@Alan
Thank you for reaching out to the Microsoft Q&A platform.
Based on the error message you provided, it seems that the deployment of the Azure Virtual Desktop failed due to an issue with the easy-button-inputvalidation-job-linked-template resource. The error message suggests that the resource write operation failed to complete successfully and reached terminal provisioning state 'Failed.
To troubleshoot this issue, you can follow the steps outlined in the Troubleshoot getting started feature Azure Virtual Desktop article. Specifically, you can select easy-button-prerequisite-job-linked-template and then select OK on the error message window that pops up.
Next, you can go to the <prefix>-deployment resource group and select resourceSetupRunbook. From there, you can select the status, which should say Failed, and then select the Exception tab. You should see an error message that provides more information about the issue<sup>.</sup>
One potential cause of this issue is that the Azure admin UPN you entered isn't correct. To resolve this issue, make sure you're entering the correct username and password, then try again<sup>.</sup> Another potential workaround is to run the Azure Virtual Desktop getting started feature again, but this time don't create a validation user. After that, create your new users with the manual process only.
If this does answer your question, please accept it as the answer as a token of appreciation.