Yes, you must file the 8962.
If you have a Marketplace policy (under Obamacare or your state's marketplace), then you should have received a 1095-A in the mail. If no, you must call your marketplace to geit (in theory, it is available online but can be difficult to find).
The purpose of the 8962 is to "reconcile" the amount of PTC that you have received.
The amount of PTC that you received (well, your insurance company received) was dependent on your estimate of your income in 2018. However, at the end of the year, you may have made more or less money than you thought, or had some life-changing event, like having a baby, getting married or divorced, getting or losing your job, etc.
If you made more money at the end of the year than you expected, then the government paid too much PTC for you, and they will want the difference back. If you didn't make as much money as you thought, the government will give you the rest of the PTC that you were merited on your tax return.
So, get the 1095-A, enter it, and the 8962 will filled in by TurboTax and attached to your return.