Hi @is0486kr,
The problem is that you are trying to copy the default code as-is. It won’t work because they are there as pointers, not as a solution (otherwise there is no work to be done 
).
In order to get things going, you need to create your own packages and custom messages and carefully adjust CMakeList.txt and package.xml accordingly.
If you want to copy anything from the code, you need to copy carefully and adjust names where necessary. In any case, you should avoid copying CMakeList.txt and package.xml.
PS: You don’t even have to use the exact code or logic suggested - just bring together all you have learnt in the previous units to solve this problem and create a solution that works.