Installation problems Bolt 2

I would like to test the Bolt 2. But after installing I get lots of (37) this errors: 

"Assets/Ludiq/Ludiq.Core/Runtime/Collections/Bictionary.cs(81,42): error CS1644: Feature `out variable declaration' cannot be used because it is not part of the C# 6.0 language specification."

First I tried with .NET 3.5 ... there were more errors (over 300). But same "cannot be used because it is not part of the C# 4.0 language spec" thing ... just with C#4.0