Hi Rocket.Chat Team.
please note that your CDN certificated are not correct.
# curl -L https://releases.rocket.chat/6.5.3 -o /tmp/rocket.chat_6.5.3.tgz
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 132 100 132 0 0 372 0 --:--:-- --:--:-- --:--:-- 372
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0
curl: (51) SSL: no alternative certificate subject name matches target host name 'cdn-download.rocket.chat'