It is not uncommon that artists release digital downloads that are not numbered, it is just a bunch of tracks written, produced and/or recorded approximately at the same time and therefore released as a group. Depending on your artistic ambitions tracks numbers are a relic from when music was distributed on a physical medium and does not make much sense in the case of digital distribution (unless you want the audience to listen to the tracks in a certain order to achieve some kind of experience beyond each single track, e.g., Pink Floyd's The Wall).

However, now when you add a release that is not numbered you are forced to add numbers = adding data that does not exist. There should be an option "Tracks on this release are not numbered" in the release tab.