Hi,
Welcome to Adobe Community !!
As you have already tried to create "batch of images" and download them with individual export jobs, my recommendation is to contact your Account Manager or TAM or your concerned Adobe contact and he/she will help you to setup a meeting with our Professional Services team they will help to download all the assets on your Dynamic Media Classic, as a bulk export.
Note : This might be a paid engagement.
In case, you are not sure about your Account Manager or TAM, please create a support ticket on Adobe Admin Console (https://adminconsole.adobe.com) or call us : (+1) 800-497-0337 or (+44) 0800 169 0454 to get that information.
Thanks,
Vikram Gaur