Looks like you are getting file names in the console wrong again. In this case, you are requesting your computer to sideload the file without providing the correct file name.Therefore the system can't fnd the file and thinks it doesn't exist.
Make sure files you are trying to load exist in the ADB/Fastboot directory and you are typing their full and correct names. In this case, type:
adb sideload xiaomi.eu_multi_leo_V184.108.40.206.LXHCNDA_v7-5.1.zip
i tried again with new name no success for me