Please ignore it. This post-installation message will be removed from the next version as it is no longer necessary (actually: it wasn't necessary since 4.0.0). FYI the white page comes from a Joomla! bug which we have already fixed since June but it will only be included in the upcoming Joomla! 3.4, scheduled for release late January as far as we know.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!