<?php
use Microsoft\Graph\GraphServiceClient;
use Microsoft\Graph\Generated\Models\UserScopeTeamsAppInstallation;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestBody = new UserScopeTeamsAppInstallation();
$additionalData = [
'teamsApp@odata.bind' => 'https://graph.microsoft.com/v1.0/appCatalogs/teamsApps/12345678-9abc-def0-123456789a',
];
$requestBody->setAdditionalData($additionalData);
$result = $graphServiceClient->users()->byUserId('user-id')->teamwork()->installedApps()->post($requestBody)->wait();