I have Avro 5.1 version on my Android tablet, but it does not work and I got a notification that "The file format is not supported". Please help me to solve it out.
You will have to report this to the developers because there is no troubleshooting information about it. I've checked various websites, but nothing was found. If you have the app installed, start it and then locate the Help section or About/Contact. Use the available contact details and get in touch with the developer while you can report this issue as well. I recommend this way because the app doesn't appear to be available on the Play Store anymore.