$programFiles = [environment]::getfolderpath("programfiles")
add-type -Path $programFiles'SharePoint Online Management ShellMicrosoft.Online.SharePoint.PowerShellMicrosoft.SharePoint.Client.dll'
$siteurl = 'SITEURL'
$username = 'USERNAME'
$password = ConvertTo-SecureString -String 'PASSWORD' -AsPlainText -Force
$outfilepath = $siteurl -replace ':', '_' -replace '/', '_'
[Microsoft.SharePoint.Client.ClientContext]$cc = New-Object Microsoft.SharePoint.Client.ClientContext($siteurl)
[Microsoft.SharePoint.Client.SharePointOnlineCredentials]$spocreds = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($username, $password)
$cc.Credentials = $spocreds
$sideLoadingEnabled = [Microsoft.SharePoint.Client.appcatalog]::IsAppSideloadingEnabled($cc);
$cc.ExecuteQuery()
if($sideLoadingEnabled.value -eq $false) {
    Write-Host -ForegroundColor Yellow 'SideLoading feature is not enabled on the site:' $siteurl
    $site = $cc.Site;
    $sideLoadingGuid = new-object System.Guid "AE3A1339-61F5-4f8f-81A7-ABD2DA956A7D"
    $site.Features.Add($sideLoadingGuid, $false, [Microsoft.SharePoint.Client.FeatureDefinitionScope]::None);
    $cc.ExecuteQuery();
    Write-Host -ForegroundColor Green 'SideLoading feature enabled on site' $siteurl
}
Else
{
    Write-Host -ForegroundColor Green 'SideLoading feature is already enabled on site' $siteurl
}