I would strongly suggest to use latest build, here’s why:
1. Problem with old model – Earlier version used “name & email” entries which meant that anybody can bid. This might seem tempting but there is grave drawback i.e. anyone can sabotage your auction.
Lets say you have an authentic auction running which have authentic bids. Now, anybody can just enter its name & fake email & give a random bid value. This totally ruins your auction.
2. No support for old model – Since, new model has been released, I wont be able to provide upgrades or support for it.
In the long run, it would always be good if you could only allow bidding for registered user.
Incase you still want old version, kindly download it here: https://auctionplugin.net/plugin/ultimate-auction.zip
NOTE: I’ll remove it once you confirm or else by tomorrow.
Take care
Nitesh