It happens when you are converting from a C6 app (not all of the examples have been updated to C8 yet.)
the IDE notices there is a LIB in the project, and since you said "yes" when it asked if you wanted to add external projects to the solution, and it didn't find clanet.app, it's asking you if indeed there is one.
you don't have it, so you say no - it's not a big deal. (And if you answer no to the first question, you won't see this one...)
cheers
Bruce