TileDB Cloud comes with two user-facing components:
Console: This is the TileDB Cloud UI you can use by signing up and logging into https://cloud.tiledb.com. On the console you can manage your arrays, see billing information, spin up a Jupyter notebook, etc. The Console Walkthrough tutorial is a good starting point for getting familiar with the TileDB Cloud console.
TileDB Cloud client: This is a library for programmatic API access of the various features of TileDB Cloud. You can use the client API to perform pretty much every action you can perform on the console (except for signing up and running Jupyter notebooks). You need to have a TileDB Cloud account to use the client, since it requires you to log in with your username/password or an API token.