This may be because of spawn protection. Try to turn it down to 0 in the Minehut Panel. If this doesn't work, send me your plugins list, I want to take a look at it.
This would not be an issue with Minehut, but I would be glad to help you. Could you tell me what version you are using and if you have any mods installed?
You must enable whitelist! To do this, enter "whitelist on" in the console, and then run "whitelist add (username)" and replace username with your name. To add more people to the whitelist, just type the same command, but with their username.
If you would like to play Minehut, you must have a premium account, which you have figured out. But, we will not give you one. If you would like to get one, you can purchase it from https://minecraft.net/.
You need to restart your server. The reason this happened is because your inventory can't fit 1222222 diamond blocks in your inventory, causing them to be dropped on the ground. Minehut has a low amount of RAM, meaning it doesn't handle excessive items on the ground well.
Hope this helps