The issue that your article discusses is searches about Americans conducted on data collected from non-Americans outside the US (via Section 702). This is not mass surveillance on Americans.
The only program that collected Americans' data en masse in Snowden's documents was phone metadata collection, but it would be a huge stretch to label the way the documents described the data as being used as "mass surveillance." It certainly doesn't paint a picture of intelligence agencies run amok spying on everybody without regard to the law and without oversight.