Having Trouble Receiving ToonBoom Studio Files

My friend gave me ToonBoom the other week and I’m having some trouble with it, in the sense that when he sends me a file to work on, I get the error message “x.tbp is not a valid Toon Boom File [E1021]”. I was wondering if anyone had a solution to this?
Thanks

Your friend should be sending you the entire zipped project folder.
Are you both using the same version of the software?

It’s possible that the file became corrupted on transfer judging
by the error message.