and it should have the Carpet HDF5 reader built in. You will need to enable HDF5 output for the variables you want to look at in your parameter file, e.g. with something like
IOHDF5::out_every = 16 # iterations
IOHDF5::out_vars = "ML_BSSN::phi" # Conformal factor
This is for 3D output. You can also output 1D and 2D slices, but if you want to do volume rendering, I guess it's 3D you are after.