There's (still) no such thing as the national popular vote

Every state has a different way of electing delegates. Some use open primaries, some closed, some semi-open, and some semi-closed. The ones that are closed or semi-closed have different registration deadlines. Some states have caucuses. Some of the state that have caucuses record votes. Some don't. Some states have huge numbers of registered Democrats who probably won't vote Democratic in the fall. And in some states, there's even a primary and a caucus hybrid.

The point is that under the Democratic system, for better or for worse, you simply can't add up all the various contests and end up with a meaningful number. If all the states used the same mechanism, the results would mean something. But that's not our current system, for better or for worse.