If you can't open the aol desktop on the windows 10 mail application. here are the guide to fix that error. you may apply it on your devices.
Reboot the computer. Delete the temp files. Run a system scan. Run troubleshooting program to detect the issue. check the internet connection. Uninstall and reinstall the program.Once you change these settings, your device will start working fine. if you can't receive the emails on aol desktop app. please check the mail setting.