What is write access to vault?

Using Cryptomator 2. I see an option to unlock the full version. One of the unlocked features is “Write access to your vaults.” Can someone explain what this is and how this is different from what exists in C2? Thanks in advance.

The free iOS version is read only.
If you want to save something into you vault, you need write access.

Well that make sense. That obvious answer didn’t even occur to me because I have been using the vault as a way to add files added from the desktop app, which allows write access, and then read them on the iPhone. Thanks for your reply.