If you renew your member area subscription you will have access to the last 5.x series install and the latest 6.x series install. AFAIK you will have to update to the latest 5.x series then upgrade to the latest 6.x series.
There are no "updaters" as they're not needed, upgrading has been how to "upgrade" the forum for some time.
If you've lost your information you'll have to contact Groupee technical support at:
https://www.infopop.com/q/q.php?action=pool_query&num=14