Let's encrypt - SSL certificate

The import via FTP is NOT the idea. Lets Encrypt supports an automatic renewal of certificates, by granting root access to a script. The script loads a key from lets encrypt, and places it on a public web location, accessible by Let's Encrypt for download to verify you have root access.

The UI should be integrated in Add Certificates, where you choose Let's Encrypt as the provider. Than the whole process can be automated. These scripts are available for Unix. 
Every day or so, a script is run to verify if the certificate needs to be renewed, and it than renews the certificate automatically if needed. 

So please forget about the FTP service upload. 

Long story, but Let's Encrypt has become the defacto standard (it is free!), for many websites and for many devices. Please implement this soon.

One extra argument. The EU GDPR requires that you have your network well secured, and state of the art. This now requires setting up a certificate, which is way to complicated for small companies as it is today. Let's Encrypt provides an easy an automated process to handle this.