The energy-dependent expectations for the full KM3NeT/ARCA detector, both for diffuse and point-like signals are presented. For the diffuse analysis, the $90\%$ C.L. quasi-differential sensitivity for 10 years of the full detector operations is computed, and compared with the IceCube measured diffuse spectrum. The whole energy range observable by ARCA~$\sim(1\, \rm{TeV}-100\, \rm{PeV}) $ is taken into account, selecting upgoing track-like as well as all-sky cascade-like events. For the point-like analysis, the differential sensitivity for several declinations is computed, selecting upgoing tracks $\nu_{\mu}$ and $\bar{\nu}_{\mu}$ charge-current interactions. Some particular starburst galaxies (SBGs) are considered such as NGC 1068, the Small Magellanic Cloud (SMC) and Circinus Galaxy. The resulting sensitvities demonstrate the importance of KM3NeT/ARCA to link star-forming processes with high-energy neutrino production within a few years of operation.