The program needs an empty folder to back up to. Many customers were overwriting their backups with corrupt data. This prevents it from happening.
Create a folder on your computer called MasterCook Backups. Create a folder inside of it with today's date. Backup to the dated folder. Then in the future create a new folder with that day's date and backup to it. If you discover you backed up a corrupt cookbook, you will have previous, older backup copies you can restore instead, before your cookbook became corrupt. It is a best practice, and some backup programs have been doing it for years.
Otherwise, you can use other programs to back up your data. See this article:
3 Ways to Create Automatic File Backup in Windows 10/11 Easily (minitool.com)