Are you trying to pull out the values of the partition coefficients or the model equations?
In order to load the model you refer to in your post, you can either open the SimBiology App by typing in the command line:
and then clicking on 'Open' and navigating to the folder where the model is.
If you want to load the model object in MATLAB, rather than in the SimBiology App, you can use the function sbioloadproject.
model = sbioloadproject('PBPK.sbproj');
parameters = model.Parameters
equations = getequations(model)
Note that the PBPK model relies on a two functions (calculateParacellularAbsorptions.m and calculateTissuePartition.m) that need to be on your MATLAB path or in your current folder in order for the PBPK model to simulate without errors.
I hope that helps.