haxe still tries to setup Visual Studio. Probably something went wrong during the installation.
It also looks like the installer was still in use, when you tried to run it again.
2015-08-28 18:37:12,321 DEBUG [SwingWorker-pool-5-thread-2] stencyl.sw.util.FileHelper: Saving downloaded file to: C:\Users\Ivan\AppData\Local\Temp\stencyl772362330028988229\sandbox\wdexpress_full.exe
2015-08-28 18:37:12,322 ERROR [SwingWorker-pool-5-thread-2] stencyl.sw.util.FileHelper: C:\Users\Ivan\AppData\Local\Temp\stencyl772362330028988229\sandbox\wdexpress_full.exe (The process cannot access the file because it is being used by another process)
java.io.FileNotFoundException: C:\Users\Ivan\AppData\Local\Temp\stencyl772362330028988229\sandbox\wdexpress_full.exe (The process cannot access the file because it is being used by another process)
at java.io.FileOutputStream.open(Native Method)
Please try uninstalling Visual Studio, kill any wdexpress_full.exe processes (if they are still running), and then reinstall Visual Studio from within Stencyl.