Place the frozen meatballs at the bottom of your Instant Pot.
Place dry pasta on top of the meatballs (if using spaghetti or long pasta, break it in half so it'll fit into the inner pot), and try to spread and layer the noodles so they don't all clump together.
Pour a jar of pasta sauce over the dry pasta, making sure most of the noodles are covered. *** DO NOT STIR ***
Pour in the 4 cups (approximately 1 jar) of water along the side of the pot. Be careful not to pour it on top of the pasta sauce. DO NOT STIR, but press any uncovered noodles down into the sauce. NOTE: You would not want too much pasta sauce to lay at the bottom of the pot since it will likely give you a "burn" error since the sauce is thicker in texture. That's why we want to pour water along the side of the pot so the thinner liquid stays at the bottom.
Close the lid on your Instant Pot and set the pressure valve to the sealing position.
Set to manual cook on high pressure (See "Special Note on Cook Time" for more detail).
Once the cooking time has ended, carefully perform a quick pressure release by turning the pressure valve to venting.
Once the pin drops, carefully open the lid and stir the pasta and meatballs. It might look a bit watery at first, but it will thicken up as it cools and gets stirred.