What is the error message?
Most newer .ai files will require Illustrator or other app that is compatible with the newer versions of .ai, There isn't many known .ai converters that will be compatible with newer .ai files. So you likely need to download the trial of Illustrator or have some one convert it for you.
Would Adobe consider offering images in png and jpeg as options?
Once a vector image is a png or jpg it no longer is a vector image. If you would rather have jpg images then uncheck vectors from the search tool.
images are supplied by independent and freelance contributors. Adobe doesn't create the files, they are just a marketplace for them. So it would be up to the individual contributor as to what format they supply.
Ok I understand.
Thanks for explaining.