Hi,
Download URL was built incorrectly after I have modified update server yesterday. WordPress may take it from the internal cache (transients). So about 24 hours may take place before it will request a fresh (valid) value from role-editor.com.
You may wait until tomorrow or try to clear cached values from the database – these records:
SELECT * FROM wp_options where option_name like '%update_plugins%';
SELECT * FROM wp_options where option_name like '%external_updates-user-role-editor%';
