Just download the app make a vault. Same it in iCloud or google drive. Now use your desktop pc and copy the files over. Done and a accessible vault in your smartphone.
Note that iCloud Drive on the Mac is a bit random about when it decides it wants to sync files. I ended up abandoning that setup after too many times of being somewhere and finding my laptop never pushed up the latest version of a file.
You can't just save the vault in Good Drive on your phone, because the vault is looking for a folder on your phone to sync to. The Drive option simply isn't there. From what I've seen you have to download another, third party sync app, to do that, and that just sounds clunky af. Obsidian charging $90 a year(!) for sync is just super lame. I can wait til they realize that.
