'Error while compiling ImageLibrary'

Can someone please help me with Quest System (ie. XDQuest)?  I have everything uploaded properly, but I keep getting this error and the plugin won't load:

Error while compiling ImageLibrary: The type 'SteamInventory' exists in both 'Facepunch.Steamworks.Posix, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' and 'Facepunch.Steamworks.Win64, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' | Line: 159, Pos: 18

This is the line it's referring to in the plugin:          

private const string MISSIONPROVIDER_TEST = "assets/prefabs/npc/bandit/shopkeepers/missionprovider_test.prefab",

Seems to semi-work on my local hosted server, but it's only giving one mission and it's not like in the ad video; it's just a basic mission giver, but doesn't read the Quest.json list in Data, even though I made it on the website with my purchase key.   I'm pretty sure I got the $15 version that doesn't work properly, so maybe the developer got the files mixed up when creating this seller page.  I hope they recognise the issue and fix it asap.

https://gyazo.com/88266ad6efea2d2510a0f3b21f462054

Write to me in discord @dezlife