Can’t do this raid

I used to have access to this raid, but ever since raids were updated, I lost access to this raid. It says I have to graduate from tier 6 starter guild to unlock. I’m currently in tier 5 starter guild. This is a problem because I have a quest to do one attempt in this raid. It is part of a two part quest that also includes two attempts in The Pit, which I have already done. This is all I have left to do to complete this quest and collect my rewards. I don’t know how to do this since I don’t think the raids will go back to how they were before.