Hello @Zandra !

First of all, backup your Dolphin site (the database + all files except from the cache, cache_public and tmp folders ), then you need to upgrade your Dolphin to the 7.4.2 version. The next step is to install UNA somewhere in the subfolder of Dolphin. And finally - go to the UNA studio->Apps Market, search and install there the Dolphin migration tool app. Launch it and follow the appearing instructions.