Background Assets：Failed to schedule download

I wrote the following code to schedule the download in extension：

AURLDownload *essentialDownload = [[BAURLDownload alloc] initWithIdentifier:url
                                                                                 request:[NSURLRequest requestWithURL:assetURL]
                                                                               essential:true
                                                                                fileSize:assetSize
                                                              applicationGroupIdentifier:YYBASharedSettings.appGroupIdentifier
                                                                                priority:BADownloaderPriorityDefault];
            NSLog(@"BackgroundAssetsTest extension Schedule essentialDownload url:%@",url);

and the delegate callback is implemented as follows：

- (void)backgroundDownload:(BADownload *)download failedWithError:(NSError *)error
{
    NSLog(@"BackgroundAssetsTest extension failedWithError: %@",error);
}

The console outputs the following error:

BackgroundAssetsTest extension failedWithError: Error Domain=BAErrorDomain Code=202 "The requested URL is not permitted to be downloaded until the application is launched." UserInfo={NSLocalizedFailureReason=The requested URL is not permitted to be downloaded until the application is launched.}

What's the problem? Scheduled downloads can only be triggered by launching the APP?