[08:04:08 ERROR SMAPI] Oops! You're running Stardew Valley 1.2.33, but the oldest supported version is 1.3.13. Please update your game before using SMAPI.
(I think this is the only important line)

[08:13:58 INFO SMAPI] SMAPI 2.6-beta.15 with Stardew Valley 1.2.33 on Microsoft Windows 10 Home
[08:13:58 DEBUG SMAPI] Mods go here: C:\Users\catmu\Desktop\Stardew Valley\Mods
[08:13:58 TRACE SMAPI] Log started at 2018-06-01T12:13:58 UTC
[08:13:58 ERROR SMAPI] Oops! You're running Stardew Valley 1.2.33, but the oldest supported version is 1.3.13. Please update your game before using SMAPI.
[08:13:58 INFO SMAPI] Game has ended. Press any key to exit.
(I copied everything just in case)

-In settings in the game it says im in 1.3.15(Started from steam)
-Shows 1.3.15(Desktop shortcut)
-Shows 1.2.33(Game folder)

Im trying to replace the Old copy in the game folder with the desktop shortcut but when i do ModdingAPI says it can't find a game

Hi @diddlekid. The version SMAPI shows is correct.

That message shows you're running a copy of Stardew Valley on your desktop, not a shortcut to the Steam folder. Try this:

1. delete the copy on your desktop;
2. see Part 2: configure Steam in the SMAPI install guide;
3. launch the game through Steam.

If that still shows 1.2.33, make sure you're opted in to the beta in Steam, then reset your game files.

GitHub issues are only used for SMAPI development tasks. If you still need help, come ask on Discord or post in the SMAPI support thread. :)