Digital download failed for full gallery or order downloads
You may find that downloading individual images works fine but downloading of an entire gallery fails. The Digital Downloads add-on’s default setting is set to build zip files of all the images in the gallery on the fly for user to save server space on your web hosting and also build a zip file of only the files the specific user needs. However, this process can be a server intense and cause the process to fail if the server cannot handle the load. This will all depend on the resources of your web server, the size, and quantity of images being put into the zip file.
If you are running into issues with larger digital downloads, please first try increasing the available memory for your WordPress installation.
If that doesn’t work, try using the alternative download method.
If you still continue to have issues please submit a support ticket as more in-depth debugging will be needed for your specific setup.