How to import a large .pst file into Outlook classic

The issue I am having:

I exported a client’s email inbox to a .pst file that is about 48GB, then imported it into Outlook on another PC. Hundreds of folders remain after the import, but the email contents of alot of the folders are empty, like they didn’t all import

Questions:

whats the best way to import large amounts of email?

is there a 3rd party tool to do this?

Due to the client’s needs, using another email program isn’t in the books

What emails system did not export from, and which email system are you importing into ?

If you open the pst file, did you see the emails ?