# URL to SharePoint site where you want to add an alert
$siteUrl = ""
# SharePoint user name you want to create the alert for
$username = ""
# SharePoint user password in plain text
$password = ""
$listname = "Documents"

# Load SharePoint client dlls (get them from nuget.org and place them along with this PS1 file)
# For instance Microsoft.SharePointOnline.CSOM or Microsoft.SharePoint2013.CSOM
[System.Reflection.Assembly]::LoadFile("$PSScriptRootMicrosoft.SharePoint.Client.dll")
[System.Reflection.Assembly]::LoadFile("$PSScriptRootMicrosoft.SharePoint.Client.Runtime.dll")

$context = New-Object Microsoft.SharePoint.Client.ClientContext($siteUrl)
$securePassword = ConvertTo-SecureString -String $password -AsPlainText -Force
$context.Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($username, $securePassword)

# Get list from SharePoint
$list = $context.Web.Lists.GetByTitle($listname)

# Load needed information from SharePoint Online
$currentUser = $context.Web.CurrentUser
$context.Load($currentUser)
$context.ExecuteQuery()

# Create new alert using CSOM for the user
$alert = New-Object Microsoft.SharePoint.Client.AlertCreationInformation
$alert.List = $context.Web.Lists.GetByTitle("Documents")
$alert.AlertFrequency = [Microsoft.SharePoint.Client.AlertFrequency]::Immediate
$alert.AlertType = [Microsoft.SharePoint.Client.AlertType]::List
$alert.AlwaysNotify = $false
$alert.DeliveryChannels = [Microsoft.SharePoint.Client.AlertDeliveryChannel]::Email
$alert.Status = [Microsoft.SharePoint.Client.AlertStatus]::On
$alert.Title = "New alert created at : " + [System.DateTime]::Now
$alert.User = $currentUser
$alert.EventType = [Microsoft.SharePoint.Client.AlertEventType]::All
$alert.Filter = "0"
# 0 = Anything Changes
# 1 = Someone else changes a document
# 2 = Someone else changes a document created by me
# 3 = Someone else changes a document modified by me

# Add the alert for the user
$newAlertGuid = $currentUser.Alerts.Add($alert)
$currentUser.Update()

# Execute creation request to the SPO
$context.ExecuteQuery();