To have your projects available on different devices, you need to make sure you're using the same account on all devices and have a good internet connection.
Here's how the project synchronisation works:
If you create a project – it is created on other platforms as well;
If you delete a project – it is deleted on other platforms;
If you are editing a project – your local (the latest) version overwrites other versions on all platforms.
Attention: never keep the same project open on several devices. That leads to version conflicts and possible loss of working progress. Always exit the project once you've finished working with it.
Stay synced and keep designing!