Hi Adrian,
You can use Wifi syncing to sync between mSecure 5 on different devices. We don't look for it or care what iCloud or Apple ID you're using. What does matter to us is what mSecure account you're using though. You need to use the same mSecure account in mSecure 5 in order to sync via any method.
Please take a look at this article to learn how to use WiFi syncing in mSecure 5: https://m7software.freshdesk.com/support/solutions/articles/36000022760-wi-fi-syncing
Adrian