Larian Studios Forums Divinity - Original Sin Divinity Original Sin - Mods Several Questions

Hey,

i was watching the 90 min basic video and tried myself.
But after adding my first terrain i can not go on because i am not allowed to save.

It allways says "Some files werenｴt saved. Please check the message panel for more information"

And the panel says:
"You need developer rights to open the file "D:/Steam/SteamApps/Common/D-OS/Data/mods/Main/Levels/Testlevel/Terrain/TerrainDRE.lsb"
"Failed to dave file D:/Steam/SteamApps/Common/d-os/Data/Mods/Main/Levels/Testlevel/Terrains/TerrainDRE.lsb"

What am i doing wrong? Because of that errors i can not go on working wit the editor.