TOI-2076 b is a sub-Neptune-sized planet (R=2.39+/-0.10R_{Earth}) that transits a young (204+/-50MYr) bright (V=9.2) K-dwarf hosting a system of three transiting planets. Using spectroscopic observations obtained with the NEID spectrograph on the WIYN 3.5m Telescope, we model the Rossiter-McLaughlin effect of TOI-2076 b, and derive a sky-projected obliquity of {lambda}=-3-15_^+16^{deg}. Using the size of the star (R=0.775+/-0.015R_{sun}), and the stellar rotation period (P_rot=7.27+/-0.23days), we estimate an obliquity of psi=18_-9_^+10^{deg} ({psi}<34{deg} at 95% confidence), demonstrating that TOI-2076 b is in a well-aligned orbit. Simultaneous diffuser-assisted photometry from the 3.5m telescope at Apache Point Observatory rules out flares during the transit. TOI-2076 b joins a small but growing sample of young planets in compact multi-planet systems with well-aligned orbits, and is the fourth planet with an age <~300Myr in a multi-transiting system with an obliquity measurement. The low obliquity of TOI-2076 b and the presence of transit timing variations in the system suggest the TOI-2076 system likely formed via convergent disk migration in an initially well-aligned disk.