With Brainity you can create lookalike OR interest-based audiences, but you can't mix both.
This is because Lookalike audiences are an automatic and broader version of Interest-based audiences. By picking interest AND lookalike audiences you are preventing the audience from working at its best, and limiting its performance. That is why with Brainity you always must choose between one option or the other.
Here is more information on Lookalike and Interest-based audiences.