Thingiverse has changed the way it organizes files for download. It no longer offers a zip file of all the files for a project. You have to download each file separately.
To download all files in a zip file, click the download link and change /files to /zip and you will be able to download the project as a zip file.
example:
change https://www.thingiverse.com/thing:248009/files
to https://www.thingiverse.com/thing:248009/zip
I’d seen something like this in another resource/forum and the OP also created a bit of script which does the “hard part” for you, although that’s somewhat of an exaggeration.