  As part of our program to identify host galaxies of known z=2-3 MgII
absorbers with the Keck Cosmic Web Imager (KCWI), we discovered a compact group
giving rise to a z=2.431 DLA with ultra-strong MgII absorption in quasar field
J234628+124859. The group consists of four star-forming galaxies within 8-28
kpc and $v\sim40-340$ km s$^{-1}$ of each other, where tidal streams are weakly
visible in deep HST imaging. The group geometric centre is D=25 kpc from the
quasar (D=20-40 kpc for each galaxy). Galaxy G1 dominates the group
($1.66L_{\ast}$, ${\rm SFR}_{\rm FUV}=11.6$ M$_{\odot}$ yr$^{-1}$) while G2,
G3, and G4 are less massive ($0.1-0.3L_{\ast}$, ${\rm SFR}_{\rm FUV}=1.4-2.0$
M$_{\odot}$ yr$^{-1}$). Using a VLT/UVES quasar spectrum covering the HI Lyman
series and metal lines such as MgII, SiIII, and CIV, we characterised the
kinematic structure and physical conditions along the line-of-sight with
cloud-by-cloud multiphase Bayesian modelling. The absorption system has a total
$\log(N(HI)/{\rm cm}^{-2})=20.53$ and an $N(HI)$-weighted mean metallicity of
$\log(Z/Z_{\odot})=-0.68$, with a very large MgII linewidth of $\Delta
v\sim700$ km s$^{-1}$. The highly kinematically complex profile is
well-modelled with 30 clouds across low and intermediate ionisation phases with
values ${13\lesssim\log(N(HI)/{\rm cm}^{-2})\lesssim20}$ and
$-3\lesssim\log(Z/Z_{\odot})\lesssim1$. Comparing these properties to the
galaxy properties, we infer a wide range of gaseous environments, including
metal-rich outflows, metal-poor IGM accretion, and tidal streams from
galaxy--galaxy interactions. This diversity of structures forms the intragroup
medium around a complex compact group environment at the epoch of peak star
formation activity. Surveys of low redshift compact groups would benefit from
obtaining a more complete census of this medium for characterising evolutionary
pathways.
