It shows it won't be playable until the 12th. I just got a notification saying it's been updated but it still it's not ready and there's no way to access it. I'm guessing I have to beat the 4th episode first? I still have to play episode 3. I have been waiting for the episodes to be ready since late October. Now I have to wait 3 days to play but I'm excited to finally play again!
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As mentioned in your title, the "Early Access" is now available. In order to unlock the Early Access for Ep5, you will need to clear up to Ep4 and then purchase the Early Access version of Ep5 with Manda.
If you prefer playing for free, you will have to wait until Ep 5 is available for Official Release.
Hope that answers your questions!