If the CA WA Agent is started as local or domain user, then it will have very restricted privileges.
When running Powershell scripts, make sure the Execution policy is set accordingly so that it can run properly. The following command allows you to check the execution policy for a user:
Set-ExecutionPolicy -List | Format-Table -AutoSize
You can change the policy to Unrestricted for testing:
Set-ExecutionPolicy -Scope User -ExecutionPolicy Unrestricted
You may additionally plan on running the agent as Local Service account. This allows the process to have more privileges.