I installed the datapack in accordance to the wiki, which says to put the zip file that is provided into the /saves/[worldname]/datapacks folder. I did that and it does not actually change the recipe, but other datapacks seems to function correctly.

The zip is incorrectly packaged, you can work around by unzipping the file and then creating the a new zip from within the folder.

Ah, yes, the additional, nested directory. I corrected dir structure and reuploaded zipped datapacks. Sorry for inconvenience and thanks!