Accessing /mnt to migrate PLEX server

My Cloud OS 5 Personal & Network Attached Storage My Cloud EX Series
1

Hello. To migrate PLEX server from my EX2Ultra to another NAS, I need to access and copy the files from:

/mnt/HD/HD_a2/plex_conf/Plex Media Server/

Anybody can help me? I have no idea how to hit this folder…