$azureAplicationId ="<your ad app application id>"
$azureTenantId= "<your tenant id>"
$azurePassword = ConvertTo-SecureString "<the secret of your ad app>" -AsPlainText -Force
$psCred = New-Object System.Management.Automation.PSCredential($azureAplicationId , $azurePassword)
Connect-AzAccount -Credential $psCred -TenantId $azureTenantId  -ServicePrincipal
#I just test to get all groups, you could do other operations
Get-AzADGroup