Depending on the browser you’re using, your save options might be worded differently in the drop down box when you right-click on a link. You could also just go directly to the library.zip file page: https://github.com/EnviroDIY/Libraries/blob/master/libraries.zip
and then click the gray “Download” button on the lower-right side of the page. Note that this is different than using the green “Clone or Download” button on the previous page. Because our library repository is linking to submodules and not actual files, that green button doesn’t work, which is why you have to download the actual “libraries.zip” file.