Hi Tomas,
If your existing EncFS volume does use features not supported by BoxCryptor yet, you can create a new EncFS volume without a Windows computer. Just be sure to use the configuration described in our Knowledge Base when creating a new EncFS volume:
https://boxcryptorsupport.uservoice.com/knowledgebase/articles/35105-can-boxcryptor-mount-encrypted-volumes-created-wit
--Robert