Sorry for the delay in responding to this.
For some more details on the situation, see my post here: https://theburrow.net/forum/view_topic/?tid=51. You are correct that the Iron rank will have beta access to the Survival server, however we are doing a staggered 2 stage beta, in that the beta will grow over time. I'm expecting the beta to expand by this point next week at the latest to include donators.
No matter when the beta has expanded, as promised, I will ensure that donators get to test the server for at least 1 week before regular players gain access. I hope this has cleared up the confusion.
Need support? Email [email protected] or open a thread on our website.