Files updated on Mac are not showed updated in the other Mac an either on the Mobile app.
Things I have tried: I tried to sync between the 2 Macs on Dropbox and it works ok. But then, it doesn’t work in the mobile app. By the way. I’m not technical at all.
I’m trying to have my Obsidian vaults updated on the 2 Macs as well as the Mobile.
To use iCloud Drive syncing for your vault(s), put them in the iCloud Drive/Obsidian folder. This folder should be created by the app. If you don’t see it, go into the mobile app, enter the vault picker (the vault icon in the bottom-left), and create a new vault. Make sure to enable the “store in iCloud Drive” option. Then, on a Mac where you’re signed into the same Apple ID, open iCloud Drive, and open the Obsidian folder. You can then cut and paste your vault(s) into that folder. Finally, on your iPhone/iPad, go into the vault picker again—your newly-synced vault should show in the list of options.
Just a heads-up: One potentially related problem that wouldn’t be covered by @ryanjamurphy’s solution: I’ve found iCloud to be inconsistent in terms of background syncing. On iOS or iPadOS, I sometimes need to open the Files app, and then open each and every bloody subfolder in my Obsidian vault folder to make sure that none of the files show the “Can be downloaded from iCloud” icon:
Hopefully the next generation of iOS will allow for greater control of what you can force sync, background sync, “pin”, etc!