Of course! You can use:
An unlisted Youtube Link [important: don't hesitate to check that your video is embeddable - more details here]
A private Soundcloud Link [important: please use a shareable link with the code called 'token'. You can access it by clicking on 'share' under the SoundCloud player on the SoundCloud platform - more details here]
Do not forget to indicate the release date. That way, if the date is in the future, the influencer will be warned that your track is not released yet and so that it cannot be shared.
Can I send a Demo on Groover? And by the way, what exactly is a Demo?
If you wish to get advice on a pre-mix or demo, you can select the 'Demo' option while you add your track information so that influencers know that you consider that your work is not entirely finished.
If you wish to get more information and advice on what a demo is and how to tailor your Groover campaign to get great results when sending a demo, have a look to this article.