To create an ad group for your Smart Display campaign, follow the same process you use for other ad groups. However, since Google Ads manages most aspects of a Smart Display campaign, targeting options at the ad group level are not allowed.
PHP
private static function createAdGroup( GoogleAdsClient $googleAdsClient, int $customerId, string $campaignResourceName ) { // Constructs an ad group and set its type. $adGroup = new AdGroup([ 'name' => new StringValue(['value' => 'Earth to Mars Cruises #' . uniqid()]), 'campaign' => $campaignResourceName, 'status' => AdGroupStatus::PAUSED, ]); // Creates an ad group operation. $adGroupOperation = new AdGroupOperation(); $adGroupOperation->setCreate($adGroup); // Issues a mutate request to add the ad group. $adGroupServiceClient = $googleAdsClient->getAdGroupServiceClient(); /** @var MutateAdGroupsResponse $adGroupResponse */ $adGroupResponse = $adGroupServiceClient->mutateAdGroups($customerId, [$adGroupOperation]); // Print out some information about the added ad group. $adGroupResourceName = $adGroupResponse->getResults()[0]->getResourceName(); printf("Added ad group named '%s'.%s", $adGroupResourceName, PHP_EOL); return $adGroupResourceName; }