You should import into UBB.threads v7.0, anything below 7.3 should work (v7.3 introduced the Global Moderator permission); you should then upgrade your install to v7.7.x.
The importer tool was created for PHP4/5, it may not operate at all in PHP7 (UBB.threads itself was not compatible with PHP7 until v7.7).
It appears your error report was for a line with evaled code; a lot of webhosts lock down their systems these days (by way of PHPs "disable_functions"), does your account have access to eval(), exec()? I believe its standard for even cPanel to set them to be restricted by default ("show_source, system, shell_exec, exec")
You may be able to adjust Rubens values to something say closer to 1000 chunks on a host these days; if you're dealing with dedicated resources (VPS or Dedicated machine) you could probably get away with 2000 to make the import go faster... Either way it is going to take a huge chunk of time.
Since the importer should be run on UBB.threads versions prior to v7.7, the line about mysql.inc.php needing updated is not correct; its just not designed to be imported to the modern builds.
