Can I call a web API from a DataCamp exercise?
They aren't banned, but they are frowned upon. Web application programming interfaces are tricky because they frequently change and break live exercises. If possible, try to avoid having exercises on calling APIs. If the license permits it, it's perfectly acceptable to create your own dataset by calling an API yourself.
If you do decide to have exercises that call external resources such as web APIs, you will be responsible for ensuring that they continue to work after the course has launched.