Hello!
You need to call the method: SetPage(int index) on TabView. (index being the index of the tab)
Currently it's only possible to do that via code, and not the inspector because we forgot to add a small method, but it will be available in 1.0.2!
If you want to fix it right now, open MaterialUI/Scripts/Components/Tabs/TabView.cs, around line 430, you'll find a method name:
public void SetPage(int index, bool animate = true)
Rename it to:
public void SetPage(int index, bool animate)
And just above it, add the following method:
public void SetPage(int index)
{
SetPage(index, true);
}