Referring to the official documentation, before running Datalab instance, the corresponding APIs should be enabled: Google Compute Engine and Cloud Source Repositories APIs. To do so, visit Products
-> APIs and Services
-> Library
and search for the APIs. Additionally, make sure that billing is enabled for your Google Cloud project.
You can also enabling the APIs by typing the following command, which will give you a prompt to enable the API:
datalab list
I made some research and found that the same issue has been reported on the Github page. If enabling API's wouldn't work, the best option would be to contribute (add a comment) in the mentioned Github topic to make it more visible to the Datalab Engineering team.