"Identity Politics" as played by Hillary, amounted to identifying some group[s], blacks, women, Hispanics, LGBT, and others, naming them, and asking them to vote for Hillary. Some did, just being named is powerful, but many did not, because Hillary never addressed their wants and grievances. She just asked for the votes. No quid pro quo. No campaign promises.
In some cases, the "identity group" wants something repellent to the rest of the country. Hispanics want easier immigration and a path to citizenship for the illegals allready in the country. This is anathema to large number of regular voters. Women want free contraceptives and abortion on demand which is anathema to large numbers of voters.
To do "indentity politics" well, you need some genuine members of the group, leaders, come out and campaign for you. Hillary didn't have any prominent blacks, hispanics or LGBTs on TV, calling for Hillary's election. Actually The Donald did better in this respect. He had Ben Carson, a highly respected black man, come out and publicly support him.
My advice to the Democrats in the aftermath of this year's election, is to go back to political basics, come up with a party platform, that states issues, that actually mean something real to voters. This requires some head banging within the party to accept some controversial issues. What to do about pipelines and transmission lines, oil exploration, charter schools, taxes, law enforcement, and more are all controversial inside the Democratic party. One reason Hillary never campaigned on any of them is that doing so would have brought a storm of criticism down on her from the numerous opponents of each and every issue.