When you are performing a Creatives Bulk Import in ad360 (https://console.ad360.media/creatives/new-bulk), you just need to upload a single .zip compressed folder containing your creatives.
There is a certain file that has to be included in your .zip folder, which will be used by ad360 to know how to handle your creatives.
If this file is not included, or improperly formatted, the Bulk Import will not succeed. So it's important you properly include the file.
You'll find several examples below to make it easy for you to reproduce the manifest.json file and update it according to your needs!
Sample manifest.json file
Note that the file name MUST be "manifest.json".
Here is a sample content:
{
"version" : "1.0",
"title" : "GoogleHtml5",
"description" : "Series 2",
"redirect" : "http://piano-by-chords.com/",
"source" : "index_720x90.html",
"backupgif" : "piano-banner2-728-90.gif",
"width" : "720",
"height" : "90",
"creativetype" : "html5"
}