In general, it is a very good idea to load the car in MFlow, even if you cannot run the simulations, as you can see if all parts are placed correctly and you might even get some useful warnings.
Now you issue sounds pretty technical and it is best to ask you specific questions in the Q&A for MFlow, which you can find here:
https://mantiumflow.com/mantiumflow-cfd ... e-support/
And as we have some new registered teams:
You should have received an email with the submission details this morning.
If not, please get in touch!