Grant Key Vault Permissions to System Managed Identity
Assign Get (Read) Key Vault permissions to the System Managed Identity using PowerShell Set-AzKeyVaultAccessPolicy
$RGName = "test-rg"
$AAccountName = "test-aa"
$Location = "UK West"
$KVName = "test-829-kv"
$SystemMI = (Get-AzAutomationAccount -ResourceGroupName $RGName -Name $AAccountName).Identity.PrincipalId
Set-AzKeyVaultAccessPolicy -VaultName $KVName -ObjectId $SystemMI -PermissionsToSecrets Get

Vault Access Policies
System Managed Identity has Get permissions
