It looks like it implies that simply updating the extra will also do the migration process? Was that not the case? Don't forget to back up first.
Are you able to download SEO tab (v2) from the extras still?
Not sure - Id suggest do a backup and download/install it and see if it gives you a migration option? Maybe setup a cloned dev site if its a live production site first though. Just be sure to backup so that if anything goes wrong you can revert though.
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