Minecraft just updated their version to 1.20.5 but Autcraft is still using version 1.20.4. This means that your launcher may be loading the update now and not let you connect to Autcraft.

To fix this, you will have to choose the proper version in your launcher when you load the game. Make sure you choose 1.20.4.

For instructions on how to do this, see: https://help.minecraft.net/hc/en-us/articles/360034754852-Change-Game-Version-for-Minecraft-Java-Edition

We will be adding a plugin which will allow people using 1.20.5 to connect as soon as it's available, however, due to the complexity in this new update, it may take some time.

Also, yes, Autcraft will update to 1.20.5 as soon as we can but again, it may take a while simply because the 1.20.5 update is so massive. Seriously, there's a lot. Go to this page of update information and scroll down... all the way down:
https://www.minecraft.net/en-us/article/minecraft-java-edition-1-20-5

So for now, please load your game in version 1.20.4 so that you can connect to Autcraft. We'll update the server to 1.20.5 as soon as we can.