  TOI-2076 b is a sub-Neptune-sized planet ($R= 2.39 \pm 0.10 {R_\oplus}$) that
transits a young ($204 \pm 50 {MYr}$) bright ($V = 9.2$) K-dwarf hosting a
system of three transiting planets. Using spectroscopic observations with the
NEID spectrograph on the WIYN 3.5 m Telescope, we model the Rossiter-McLaughlin
effect of TOI-2076 b, and derive a sky-projected obliquity of
$\lambda=-3_{-15}^{+16\:\circ}$. Using the size of the star ($R=0.775 \pm0.015
{R_\odot}$), and the stellar rotation period ($P_{\mathrm{rot}}=7.27\pm0.23$
days), we estimate an obliquity of $\psi=18_{-9}^{+10\:\circ}$ ($\psi <
34^\circ$ at 95\% confidence), demonstrating that TOI-2076 b is on a
well-aligned orbit. Simultaneous diffuser-assisted photometry from the 3.5 m
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 $\lesssim 300$ Myr 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.
