When you are connected to your repository and you do not see the Import button located in the upper-right corner of Nastel XRay, it means that there is no streaming token defined.
You can setup streaming using a personal token. To do this, select the main menu and then under User Settings, select Personal Tokens.
If you do not have any personal tokens, create one by selecting Generate Personal Token. If you have an existing option, you can change it as shown below.
Make sure that both Stream (sending data in) is Active (green). You can also set Query (getting data) Active if you want to access the repository data via the REST API and the mobile application.
Logout and back in again. The Import button will now be available to import your data.