This package is NOT part of Qiskit. You can find the Qiskit repositories here. And here is how to install Qiskit.
QiskitQuantumInfo.jl is an experimental package that might be interesting to expert Qiskit users.
This package mirrors in Julia some qiskit data structures (in Python). At present these data structures are used as an intermediate form in translating operators from QuantumOps.jl to qiskit data structures.