Does Desktop app/ vault and mobile App /vault speak with one another ??
So if i encrypt a file using my desktop app can I read it on my phone if i have the mobile app?
if no then what is the purpose for the cloud encryption ??
They seem completely independent.
If this is not the case, can someone please advise how to read my encrypted files on all my devises.
Yes, you can read all files on all devices.
You create a vault with one device, and just add it to all other devices.
See here: https://docs.cryptomator.org/en/latest/
If you have problems with this, please specify them.
Thank you Michael for your reply.
I created a vault in my icloud using my mobile app I called it (Vault M )
Then i went to desktop app and i selected add existing vault .
Here a new window opened and i selected icloud then i saw ( Vault M ) , I selected it but the window didn’t allow me to click open to add it because the open button was grayed out.
This process also didn’t work vice vera .
Hi. Please select the masterkey file that is in the root of your vault. Then you should be able to add the vault.
You are a star ,now files are talking after using the master key as advised , thank you.
One more thing, 
icloud drive on my phone is called FILES.
If i select on my mobile cryptomator app > icloud drive > -find existing Vault- it can not see any Vaults that i created earlier on my desktop app - ( iclouds appears empty)
however, when i create a NEW Vault using the MOBILE cryptomator app into icloud then it appears on the desktop app / ICLOUD on my desktop
( and that creates a synchronized vault )
By the way - with google drive it works both ways .
Hi.
If you crate a vault with your mobile phone on iCloud, you will notice a pdf file that is created on iCloud in the folder „Cryptomator“. Here you can read that a vault has to be created in this Cryptomator folder, to be found with the mobile apps . I guess you haven’t created your vault in a Cryptomator folder when you created it with the desktop app.
All sorted , I appreciate your support Micheal .
2 things I learned which sorted the problem