ERROR: please confirm the keyfile is match and keyring plugin is loaded
I have solved my issue:

Make sure that the backup taken by xtrabackup and the keyring file in /var/lib/mysql-keyring/keyring are from the same server.

Also after copying the keyring file to the destination server, make sure to chown mysql:mysql to it.

The Keyring file should be copied as is not the contents of the file.

To verify if things are working, you can create a new DB and some new tables, also insert some data, that are encrypted then run the following 

SELECT TABLE_SCHEMA, TABLE_NAME, CREATE_OPTIONS
FROM INFORMATION_SCHEMA.TABLES 
WHERE CREATE_OPTIONS LIKE '%ENCRYPTION="Y"%';


You need to get the result tables. Now try to select from those tables, you should see the data inserted.