We can support any third party SSL cert, including Let's Encrypt - Free SSL/TLS Certificates. Everyone can import ssl cert from SSL manager in hosting control panel for free.
We cannot automatically request and install certificates currently for such ssl type. To get ssl cert from Let’s Encrypt, you have to install software that uses the ACME protocol to your computer. Later, you can export ssl cert to pfx format and import it to your site from hosting control panel.
For more, please see