No the polls were not right as many predicted a landslide to Hillary.
You didn't read your source.
"It’s also relatively easy to address the case of presidential primary polls: They were pretty darn bad in 2016, with an average error of 10.1 percentage points. Polling the primaries is hard — the average polling error in all presidential primaries since 2000 is 8.7 percentage points. But primary polls
aren’t usually as bad as they were in 2016. Because voting in general elections operates along
increasingly predictable demographic lines, pollsters can use demographic weighting to make up for other problems in their samples. They don’t always have that luxury in the primaries, where demographic coalitions are more fluid and turnout is more difficult to model. Polling in the 2020 primaries could be a pretty wild ride."
10% is a huge margin of error especially when used to predict the results of an election.