If you download cif-file corresponding to the primitive unit cell structure, and convert it from Triclinic to Hexagonal unit cell type in the Lattice parameter plugin (note to use Fractional instead of Cartesian). You may also use a new plugin in the Builder to detect symmetry of the structure in the Crystal Symmetry Info, and then apply it to the structure.
Band structure analysis object will then compute the band structure along the symmetry k-lines corresponding to hexagonal cell. If you do DFT-LCAO calculations using default settings of QuantumATK, you will get a band structure similar to that in the database. It is not exactly the same, because one should find out which DFT functional was used in that calculation in the database, as well as other computational settings such as basis set, pseudopotential, k-point sampling, total energy tolerance, density mesh cutoff for LCAO or wave function cutoff for the plane-wave basis set and so on.
