Help: Can't unlock vault

Has this been seen before?
Do I need to use recovery key?

Goes to this screen when I click red cross, and stays here indefinitely.

You have configured in your vault setting a folder as mount point, that is not empty.
Folders that are custom mountpoints have to be empty because Cryptomator wants to write its vault content into it.
Please go to the settings of your vault and either choose an other (empty) folder as custom mount point, or disable custom mount points and use a drive letter.

Thanks @Michael !! I tried to get clever and set the mount point as the folder where the encrypted files lived lol.

Quick question: I saw that the iOS app costs £8 to download.
I started using Cryptomator on Mac cos I think it was free/open-source vibe. Is there anyway of accessing files free on iOS devices? / what is justification for those apps costing?

1st of all: yes, the desktop app is open source and follows a „pay what you want“ idea (including the option to pay nothing at all)
2nd: the mobile apps are open core. Means the core (the encryption library) is open source, but the complete app is not and you’ll have to either create your own app or buy the one Cryptomator has built for you.
Please read this to answer your question why these apps are not free.