@ericmwalk I’m pleased that you managed to post from Tot using the Shortcut.
I’m guessing that the error has been caused by the last section which you actually don’t need. By the last section, I mean a few lines that I added at the end so that the text from Tot is saved to a text file, the filename for the text file being the date and time of the post.
I have since updated the Shortcut (same link) so that it includes an extra comment explaining what is going on at the end.
If you don't want to save the Tot post to a text file, you can delete that last section.
If you do want to save the Tot post to a text file, you will need to specify in the Append action the location for where the text file is to be saved. My guess is that you got the error because the place where the file is saved is currently set to a place in my iCloud Drive!
I hope that this is clear but if not, please let me know.