Try this:
1. Re-install Blockland.
2. Download IGSO.
3. Navigate to your Blockland folder.
This has your Blockland.exe, so find that.
4. Move Add-Ons !Located Inside IGSO(v2.47).zip and drag and drop into your Blockland folder.
Side-Note: Be sure NOT to drag and drop ONTO anything, especially another folder. People hate when they get stuck downloading Add-Ons/Add-Ons/Add-Ons/Add-Ons/Add-Ons/Add-Ons/Add-Ons/Add-Ons/Add-Ons/
Add-Ons/Add-Ons/Add-Ons/Add-Ons/Add-Ons/Add-Ons/Add-Ons/Add-Ons/Add-Ons/
Add-Ons/Add-Ons/Add-Ons/Add-Ons/Add-Ons/shapes/blah.dts