Change default user's directory and force them to only use the mounted storage

I have an installed Nextcloud on my VPS with below information:

  • Nextcloud version 13.0.0
  • OS Ubuntu 16.04
  • Apache V2.4.25
  • PHP V7.0.22
  • Storage 20GB SSD
  • RAM 1GB
  • A mounted FTP Storage (to store all my cloud files except system and apps)

I need to change default user’s directory into that mounted storage. Or take their permission to add their files out of that at least.

Thx a lot