ToME: the Tales of Maj'Eyal

I am currently playing a bit of TOME while house sitting someones house. I took the download file from the webpage and installed it on their PC and I am playing offline due to no internet at the house I am sitting. I have noticed that I cannot access the vault or stonewardens or the expansion. I am doing something wrong ? I have bought the game and the expansions all via steam ages back and just downloaded the game zip from the main webpage to play at the other house.

Since the vault is online storage of items, I really don't see why you would expect that to work offline...
If the game can't verify that you have paid for it, it can't give you paid content.

To recognize that you bought the expansion on Steam, you should probably download it through Steam, not the main game site I think.