The other way to install Terraria mods is by usingtModLoader, which some mods can only support. This is a separate piece of community-made equipment that will create a larger Texture Pack or Mod option in your Terraria settings.You can install it from Steamby searching the Store for "tModL...
Again going back to Terraria when I was trying to host a tModloader server a year back, everything worked until tModloader tried to do anything steamAPI related. AFAIK this has been addressed in the rewrite of tModloader by them adding an no-steam toggle but I digress. Really, I'm ...