I see that you can import characters from Ultima IV to Ultima V, but when I clicked the "import" option the game just crashed.

Any ideas on how to do this?

Take a look here: https://www.gog.com/forum/ultima_series/ultima_series_ressource_collection/post1

Scroll down to Ultima V and fixparty.exe where it says:

FIXPARTY.EXE: this DOS exectuable fixes your Ultima IV save file (PARTY.SAV) if you get an error when trying to import a U4 character. Run the EXE, type the letter of the drive that has the save file and that should do it.

PS: Since the link in the original post seems to be dead, use this one: https://www37.zippyshare.com/v/NIl0d9TP/file.html

Thank you!! Much appreciated :-)