  Gaseous flows inside and outside galaxies are key to understanding galaxy
evolution, as they regulate their star formation activity across cosmic time.
We study the ISM kinematics of 330 CIII or HeII emitters, using far-UV ISM
absorption lines detected in the VANDELS spectra. These galaxies span a broad
range of stellar masses M$_\ast$ from $10^8$ to $10^{11}$ M$_\odot$, and SFRs
from 1 to 500 M$_\odot$/yr, in the redshift range between 2 and 5. We find that
the bulk ISM velocity v$_{ism}$ is globally in outflow, with v$_{ism}$ of -60
$\pm$ 10 km/s for low ionization gas traced by SiII 1260 Angstrom, CII 1334,
SiII 1526, and AlII 1670, and v$_{ism}$ of -160 $\pm$ 30 and -170 $\pm$ 30 km/s
for higher ionization gas traced respectively by AlIII 1854-1862 and SiIV
1393-1402. Interestingly, BPASS models are able to better reproduce the stellar
continuum around the SiIV doublet than other stellar population templates. For
individual galaxies, $34\%$ of the sample has a positive ISM velocity shift,
almost double the fraction reported at lower redshifts. Comparing v$_{ism}$ to
the host galaxies properties, we find no significant correlations with M$_\ast$
or SFR, and only a marginally significant dependence (at $\sim 2\sigma$) on
morphology-related parameters, with slightly higher velocities in galaxies of
smaller size (probed by the equivalent radius), higher concentration, and
higher SFR surface density. The outflows are consistent with models of
accelerating, momentum-driven winds, with densities decreasing towards the
outskirts. Our moderately lower ISM velocities compared to those found in
similar studies at lower redshifts suggest that inflows and internal turbulence
might play an increased role at $z>2$. We estimate mass outflow rates
comparable to the SFRs of the galaxies, and an average escape velocity of 625
km/s, suggesting that most of the ISM will remain bound to the galaxy halo.
