I'm sure that many who use obsidian already knew of this plugin. But if you just need a quick and free way to sync your notes between devices this plugin is quite handy.
⚠️ This is a community plugin - Not been maintained for 2 years ⚠️
Remotely Save - https://community.obsidian.md/plugins/remotely-save
Sync notes between local and cloud with smart conflict: S3, Dropbox, webdav, OneDrive, Google Drive, Box, pCloud, Yandex Disk, Koofr, Azure Blob Storage.
Basically the only thing you have to do (after installing obsidian) is to create a New Vault with the same name (exp. "FkyGoogle123") in all your devices.
Then go in the vault setting
Community plugins> and search "Remotely Save"
Once installed click "option" and select "chose a remote service". After that, authenticate with the Auth of your service and it's done.
A new Sync option will now appear in the vault setting menu on the left. Click it to sync your file.
I ended up just paying for Obsidian Sync. It's not very expensive and I really don't want to depend on Google, Apple, and Microsoft to make syncing work cross platform.