Thank you for
reaching out on the community and telling us about your issue. I do apologize for the issue you're having. I was taking a look at the error and saw it seems to be an issue that sometimes happen moving/creating a file on an external drive. I've found a discussion on the apple community board with an answer from a specialist with a couple of things to try. I'll link that down below. https://discussions.apple.com/thread/250882965
I would recommend taking a look at the discussion and trying out some of the fixes that were provided by the specialist. Once you have a chance to read and try out some of the fixes recommended let us know how it goes!