About backup method

Please let me know.
I'm using "imix16Band".
Save the current channel settings on the iPad you're using and upload that file to DropBox.
I get a message "Open Project Error Error Error(s)ocred" when I try to download and open the uploaded file to my backup ipad.

And I can't open the file.

The two iPads I'm using are both Model A1709 and both ipadOS are 13.4.1.
The version of imix16Band is 7.5.5.
The PC that took the backup is MacBook Air (11-inch, Early 2015) and OS is MacOS Mojava version 10.14.2.
The version of itunes is 12.9.2.5.
The audio channel was loaded with songs from the Music app.
The backup iPad has restored the backup data from the iPad I'm using now, so the Music content is the same for both.

I have a lot of channel settings saved and it would be a hassle to save them one by one to another iPad.

It's a great app, so it would be even better if you could figure out how to back it up.

I look forward to working with you.