The Download page is … overwhelming. We ought to give serious thought about how to make it less overwhelming, both for Translators and new users.
To start with, the initial Note dialog says:
Different data format to the GRAMPS 3.4 series. Full Python 3 support only as Python 2 support dropped. Uses GTK+ 3 GUI. Default database is now SQLite. Lot of updates see: What’s new?"
That first sentence is: antiquated, alarming and unhelpful. It does not link to explanation of what the change was, why a format change was necessary, how to determine which variant data you have, nor what to do if you have old/new format.
If I knew any of those items, I would fix the sentence. But that pre-dates my experience with Gramps.