AWAITING RESPOND EpicSpawners not working

[Morgen Freemen]

Hi there!
Currently I have installed the latest version of EpicSpawners on here; https://blackspigot.com/downloads/epicspawners.18656/
But, I'm getting this error in console, every time someone clicks on "Boost Spawner"

I'm running a 1.16.4 server

[20:40:42] [Craft Scheduler Thread - 1/WARN]: [EpicSpawners] Plugin EpicSpawners v7.0.3 generated an exception while executing task 3988
java.lang.IllegalArgumentException: Size for custom inventory must be a multiple of 9 between 9 and 54 slots (got 0)
        at org.apache.commons.lang.Validate.isTrue(Validate.java:136) ~[server.jar:git-Spigot-37d799b-3eb7236]
        at org.bukkit.craftbukkit.v1_16_R3.CraftServer.createInventory(CraftServer.java:1669) ~[server.jar:git-Spigot-37d799b-3eb7236]
        at org.bukkit.Bukkit.createInventory(Bukkit.java:1095) ~[server.jar:git-Spigot-37d799b-3eb7236]
        at com.songoda.epicspawners.core.gui.GuiHolder.newInventory(GuiHolder.java:34) ~[?:?]
        at com.songoda.epicspawners.core.gui.Gui.createInventory(Gui.java:785) ~[?:?]
        at com.songoda.epicspawners.core.gui.Gui.generateInventory(Gui.java:765) ~[?:?]
        at com.songoda.epicspawners.core.gui.CustomizableGui.generateInventory(CustomizableGui.java:131) ~[?:?]
        at com.songoda.epicspawners.core.gui.Gui.getOrCreateInventory(Gui.java:757) ~[?:?]
        at com.songoda.epicspawners.core.gui.GuiManager.lambda$showGUI$1(GuiManager.java:106) ~[?:?]
        at org.bukkit.craftbukkit.v1_16_R3.scheduler.CraftTask.run(CraftTask.java:81) ~[server.jar:git-Spigot-37d799b-3eb7236]
        at org.bukkit.craftbukkit.v1_16_R3.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:54) [server.jar:git-Spigot-37d799b-3eb7236]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_252]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_252]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_252]