I would encourage you to have default columns of at least post title and download button so your block works out of the box. Nothing is displayed if the download button column is not added. So it should be in by default.
Additionally, the columns section doesn’t like having two columns with titles next to them. One gets deleted. you have to put them in between columns with no title for them to stay. After a save and reload of the block editor you can add another or move them next to each other. You might want to look into that.
Finally thought, why can’t I edit an existing column and give it a title. Why do I have to delete it and put it back in?
I feel like these are more bug reports than a feature request, but this is where your forum sent me.
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