Data encryption is only used for the on-disk storage for data within the server. Whenever clients access that data, it is presented in unencrypted form (although the communication with those clients may itself be encrypted using SSL or StartTLS). Replication, the communication of updates between replication servers, is always encrypted using SSL. Each server may apply data encryption in a completely independent manner and have different sets of encryption-settings definitions. It is also possible to have a replication topology containing some servers with data encryption enabled and others with it disabled.
However, when initializing the backend of one server from another server with data encryption enabled, then the server being initialized must have access to all encryption-settings definitions that may have been used for data contained in that backend. To do this, perform an export of the encryption-settings database on the source server using bin/encryption-settings export and import it on the target server using bin/encryption-settings import.