Did you create the sub-project in the vault structure? You seen to indicate that you only did so on a temporary location? This does not automatically transfer into the vault location.
I see, so it sounds like I still need to manually create a folder for a new project on the C drive
where the Administrator set up for my pdm work. So if I check a file into my project folder on the "C", does it at the same
time check it into wherever the work group pdm server is located? Is that pretty much what's happening?
No it does not. You can work on the project wherever you choose but it will not be within the vault. The vault is a secure repository for the files. You never work on original files within it, only on copies that have been checked out.
There is no automatic filing within the vault. You can check the files into whichever project or subproject you decide.