@AlexMKTD the command to install is listed on the github page, I use the interactive install.
This method may not be suitable if needing help to configure and best to stick with standard version shipped with Hestia as installs will not be exactly the same eg os version, installed services, configuration etc.
bash <(wget -O - vtb.cx/nginx-ee || curl -sL vtb.cx/nginx-ee) --interactive
As I am not the developer of this I can not provide support for it . My nginx.conf was untouched and just located the .conf files location and made own extra settings from original ones.