Thank you for contacting us and I'm sorry about the issue you are experiencing. mSecure 5 cannot use your previous sync files. mSecure 5 sets up a different Dropbox file structure and sync file. However, mSecure 5 can restore from a.msim backup file created in the previous versions.
You can learn how to download our previous versions here: https://support.msecure.com/en/support/solutions/articles/36000064249
Since the older version(s) of mSecure isn't a cloud-based app, there is no way to "sign in" to an account where your information is stored online. Because of this, each older version of the mSecure's login password is device specific and your information is not automatically restored when an older version of mSecure is installed or reinstalled on a mobile device.
Instead, you can set up Dropbox syncing in mSecure 4 to restore your previous mSecure 4 sync information. Additionally, we have an automated reminder in the older iOS app for making backups, so it is possible that you made an email backup some time in the past. Please search in your email accounts to see if you can find an email with "mSecure", "mism" or "mscx" in them. If you find an email backup you can use this guide to restore from an email backup file: https://support.msecure.com/en/support/solutions/articles/36000022240 or in mSecure 5: https://support.msecure.com/support/solutions/articles/36000064291