acreom is by default a local-first tool. This means everything you do in acreom is stored on your desktop device in plain text Markdown. When creating a new vault, you will have to select a path in your file system you want your files to be stored at.
You can create new Vault in the Vault Menu.
A vault in acreom can either be local only and work in a fully offline fashion or haveacreom Cloud enabled for sync, integrations, web access and more.
Using 3rd party sync services for Local Vaults other than icloud has not been fully tested yet and might cause unexpected behaviour.