Hello Piero,
No, there is no version compatible with PHP 5.3.3 because all PHP versions before 5.3.4 had severe bugs regarding namespaces, late static binding, closures and other language features Akeeba Solo needs to work. Moreover, PHP 5.3.3 is five years old and over eighty (80 – yes, eighty, it is not a typo!) releases behind. In computer terms, this is ancient.
You MUST upgrade your PHP version to at least PHP 5.3.29. Even that version is end of life since August 2014, but at least it's not five years old. Older versions of PHP 5.3, including 5.3.3, have severe security issues which can and are being used to hack servers.
Even if your ancient version of CentOS doesn't provide a package for a new version of PHP you can very easily compile it yourself – or, at least, your host can. Take it from a PHP developer who, unlike your host staff, is not supposed to be a systems administrator but can and does compile PHP by himself on his test servers. Not to mention that most server management solutions such as cPanel offer the option to compile PHP through an interface that almost anyone (and most certainly a server engineer) can use.
Nicholas K. Dionysopoulos
Lead Developer and Director
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