For some reason, perhaps you don't want to run a daemon or let Letsencrypt have access to your production server.
There is a way to use it like a normal CSR/CA setup in manual mode.
./letsencrypt-auto certonly --manual -d realtechtalk.com - www.realtechtalk.com
Eventually you will get prompted to create a certain path and file with certain data:
Create a file containing just this data:
Casdfasfadsfsad........
#if you have nvidia make sure you install the nvidia-cuda-toolkit so hardware acceleration can be used
wget http://ffmpeg.org/releases/ffmpeg-3.3.2.tar.bz2
tar -jxvf ffmpeg-3.3.2.tar.bz2
cd ffmpeg-3.3.2/
./configure --disable-yasm
install prefix /usr/local
source path ........