Ninja’d by @HibiscusKazeneko, but this should still be helpful.
Because of how MusicBrainz handles recordings, most users (myself included) prefer finding something that can be roughly described as a release to sort otherwise-individual songs into. Soundcloud playlists (that do more than collect whatever the compiler found interesting) are one such good excuse. Looking at yours, it’s more than close enough to an album to count for the purposes of this site. And as for it not existing, sure it may not be possible to buy or download, but I can still hear it perfectly well when I click the play button .
In general, MusicBrainz strongly discourages deleting information. Merging with other instances, definitely, and if something is spam or a complete mistake then you can probably get the deletion passed, but there’s very little requirement for notability. To paraphrase the data removal policy page: the fact that someone else took the time to add the playlist means that its presence in the database (and its existence) has value.
To the website maintainers: I had to resort to searching the documentation to find that page. There’s a chance I missed something obvious, but that seems like something that should be easy to get to, not one that you need to already know exists before you go looking.