MUSE IFU spectrum of the young massive star cluster 5.1 extracted from six apertures (thin black line) and the X-shooter long-slit spectrum of 5.1l knot (bold blue line). The key confirmed features indicating the presence of VMS in the stellar cluster are marked with shaded light red strips, and the dark orange line shows the best-fit F_λ ∼ λ^β, with β = −1.71. The shaded gray strip indicates the (absence of) O Vλ1371 line, which usually is an indicator of VMS too. Prominent P Cygni of N Vλ1240 and the strong emission part of the C IVλ1550 indicate the young age of the stellar cluster (bold black markers). In the bottom panel, the 1σ errors of both spectra are shown. Other detected interstellar features and stellar features are marked with dashed red and green lines, respectively.