If you have the reference for that lattice constant, share it... I do a short search and I cannot find something similar. For example in
https://doi.org/10.1063/1.1726009 says that the lattice constant is 5.3A.
About materials Project data, is worth mentioning, the calculation was done using just the gamma point, which does not appear to be a converged calculation. Also the MP lattice constant is larger than experimental data.
Probably if you use a higher kpoint grid, higher cutoff and a little bit larger basis set, your calculation will get closer to experimental data, but do not think GGA DFT functionals (PBE among others) will give you exactly the correct lattice constant. Depending on what you want in terms of precision, maybe a hybrid functional will be necessary to improve the lattice constant, but remember that hybrid functional are more expensive than GGA ones... you have to define a proper balance between precision and cost.
regards