I had not realized it, but I had already downloaded the Next Generation Science Standards form there and placed them in Moodle. Just a quick look, but I didn't see something that I recognized as C3 standards. Anyway, this is how I did it for NGSS.
This image they use for the download is actually two. The one I used is the left side 3 linked balls. Right click on it and select Save link as. I then always add the text name before completing the save to my local computer. This gives an XML type file which we need.
In Moodle when you go to Administration > Site Administration > Competencies, select Import competency framework from RDF. On the resulting page, Choose the file you just save. Set the scale to Default competence scale then click on Configure scales and mark Competent - Default and - Proficient, then Close and Import. Depending on your server it might take a bit as there are 353 competencies to create. Note: If you have your own scale set up, you can use it.
Hope this works for you.
Just in case I've attached a copy. To use it in Moodle, use the Import competency framework, instead of the Import competency framework from RDF.
Next Generation Science Standards-D2454348-20170214_1817-comma_separated.csv