Pro Series is a PC program, although you need the online to connect to something. PS isn't offline(although they can be) so you should always be able to add a client.
The IRS isn't processing e-files, but that shouldn't stop you from working.
ProSeries is a program installed on your computer, you should be able to create a new client file without any issues, you just wont be able to Efile it.
What happens when you attempt to create a new client?