ODM files are used to download audiobooks to OverDrive's app. Sometimes your computer doesn't open ODM files correctly when you try to download an audiobook, meaning that the audiobook won't open automatically in OverDrive. This is a file association error, which you can resolve using the steps below.
Associate ODM files to OverDrive's app
Locate the ODM file, and control-click on it.
You can use the Search bar in Finder to look for ODM files. Try using *.odm as a query.
Click Get Info to display an information window.
Expand the Opens with section.
Click the drop-down box, and select OverDrive Media Console.
You may have to select Other to find OverDrive Media Console.
Click Continue, then close the info window.
Borrowed audiobooks will now automatically open in OverDrive's app.