There are many ways to sync Obsidian for free. The official site lists several at https://help.obsidian.md/Getting+started/Sync+your+notes+across+devices https:

There are many ways to sync Obsidian for free. The official site lists several at https://help.obsidian.md/Getting+started/Sync+your+notes+across+devices https://help.obsidian.md/Getting+started/Sync+your+notes+acr..., or try https://github.com/denolehov/obsidian-git https://github.com/denolehov/obsidian-git - and there are more.