Do I need to match RAM timings exactly when upgrading my laptop?

No. Any DDR4 8GB stick will work, but you might lose a little performance or get rare crashes if you mix wildly different speeds/timings. Ideally the two sticks match, but if you can’t find the exact same model, grab another 8GB DDR4-3200 and it’ll be fine—it’ll just run both sticks at the slower one’s specs. Just make sure it’s a laptop SODIMM, not desktop DIMM.