Players on my server report that they get this message:

"You've not got enough pipes to build that I'm afraid"

Do the plugin require pipes in inventory?

In the config you can configure how many pipes each permLevel is allowed to build. If you set pipeLimit to -1 (like in hqm) then it will remove this limit

  "permLevels": {
    "sticks": {
      "upgradeLimit": 0,
      "pipeLimit": 15
    },
    "wood": {
      "upgradeLimit": 1,
      "pipeLimit": 25
    },
    "stone": {
      "upgradeLimit": 2,
      "pipeLimit": 35
    },
    "metal": {
      "upgradeLimit": 3,
      "pipeLimit": 45
    },
    "hqm": {
      "upgradeLimit": -1,
      "pipeLimit": -1
    }
  }

Thanks, I just found an old post about it