Dataset repositories, also known as research data repositories, provide researchers with a stable place to store and provide others with access to their research data.
Depending on the research discipline, data can often be deposited in one or more data centers (or repositories) that will provide access to the data. These repositories may have specific requirements :
(UO Libraries. "Data Repositories". Research Data Management)
Some dataset repositories also have their own guidelines and suggestions for how to construct a data citation, which elements to include, and where to find those on the site. Look carefully around the repository's website to see if you can find any information about citing their data.
If you are interested in looking at some research data repositories here is a very short list. Databib maintains a very extensive list of research data repositories if you would like to explore further.