I got the regular edition on Steam but wanted the Premium version so I bought it here. Surprised to find the one I bought on Gog is just the regular edition even though I paid $49 for it. I figure there's something basic I don't know, how do you get the missing items?

Made it to the Adventurer's guild but the mace thingy isn't lit up so I can't get it...

Look in your game installation folder for "Card_FourRewards_Bard.pdf". It has a code for unlocking the items. The code is input in options/gameplay.

Kael’s Axe, the Fire Horn and the Bardic Brian Booty items are in the Old Adventurer’s Guild. The Red Boots are on a corpse in a hanging basket in the Grand Plaza area of Skara Brae Underground.