Hi Zap. I'm Greg, an installation specialist, 10 years awarded Windows MVP, and Volunteer Moderator, here to help you.
Try uninstalling it in Settings > Apps > Apps & Features, restart PC, then reinstall it from a fresh download on their website here: https://www.freedownloadmanager.org/download.htm
If that doesn't work then it may be deprecated with the latest version. New versions in WIndows 10 replace new WIndows operating systems so there will be software, drivers and hardware that are deprecated with each new version.
If so you can try the free Download manager which is a Chrome extension here: https://chrome.google.com/webstore/detail/free-... which is vetted by Google so reliable.
There is a good comparison of Download managers here:
https://www.techradar.com/best/free-download-ma...
I hope this helps. Based on the results you report back I may have other suggestions if necessary. If you will wait to choose whether the problem is resolved, then I will continue to help until the problem is fixed.
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