Unable to install the plugin in Elasticsearch 6.4

[Former user]

Hi, Could you please give me some advice on how to install the plugin in Elasticsearch 6.4, since I'm getting the following error after executing the command:

<./bin/elasticsearch-plugin install file://tmp/elasticsearch-analysis-seunjeon/elasticsearch-analysis-seunjeon-6.1.1.1.zip>

ERROR: This plugin was built with an older plugin structure. Contact the plugin author to remove the intermediate "elasticsearch" directory within the plugin zip.

Could you please help me? Thanks