Hello again, the only thing I can think of is that you maybe placed the Smapi program into the Mod folder. If yes, take it out of the mod folder and place it outside of the game.
-open the file
-click on the 'install on windows'.
-it asks you where do you want to add your smapi.
-it gives you two choices, first is the one where do you have your game installed. second is another path, but you can ignore that.
-you put 1 into the box and click on enter.
-then it asks you if you want to install or uninstall.
-click 1 in the box again and click on enter and it is installed.
then you go to your steam library and look for Stardew Valley in your library.
click with the right mouse button on the game and it shows you a box.
click there on 'properties'.
then you get another box.
and in launch option you need to place:
"C:\Program Files (x86)\Steam\steamapps\common\Stardew Valley\StardewModdingAPI.exe" %command%
I hope it helps. if not, let me know and I will look into it again.