To give others access to your encrypted files, they will need access to the Cryptomator vault and your password.
How do I give others access to the Cryptomator vault?
This depends on the cloud provider you are using. Some allow to share files using the context menu in your file system, others allow to share files using the web interface. Consult the documentation of your cloud provider on how to do it. You have to share the folder with the vault name which contains the file
How do I transfer the password?
In general, you should only transfer the password in a secure way. Using an encrypted messaging service, encrypted mail, or similar are feasible. If possible, you may tell the password in person.
What if I only want to share some of my files?
You can create as many vaults as you want. Share one with your family, one with your colleagues, and use one privately.
However you can’t share individual files from within a vault.
Can I revoke access to the vault by changing the password?
No. Even after changing the password, another user could still access the vault using a backup copy of an old key. To disallow access, you will have to create a new vault with a new password and migrate all contents. Only then, everything gets re-encrypted.
Please be aware that even if you do that, a user who once had access may have made copies of all files stored in the vault at that time.