Think I've got it..
$path = "c:\DIRECTORY"
If(!(test-path $path))
{
New-Item -ItemType Directory -Force -Path $path
}
$url = "https://www.pulseway.com/download/Pulseway_x64.msi"
$output = "C:\DIRECTORY\pulseway.msi"
(New-Object Net.WebClient).DownloadFile($url, $output)
start-process -FilePath 'c:\DIRECTORY\pulseway.msi' -ArgumentList '/qn username=PULSEWAYUSER password=PULSEWAYPASSWORD group="GROUIP NAME" server=PULSEWAY-ENT-SERVERNAME' -wait