I was able to find your repository and inspect your pipeline configuration (below). The reason your pipeline is sitting in a pending state because you are trying to execute pipelines on Windows, however, Drone Cloud only supports Linux.
- name: dotnet-build
- dotnet --version
When you try to execute a pipeline for an unsupported platform it will sit in a pending state for a period of time and then will eventually be killed. If you need to execute pipelines on windows you will need to install Drone on your own server; you cannot use Drone Cloud with windows.