The faster way to switch ONLYOFFICE Groups to HTTPS is to use the provided script. It is located here:
/var/www/onlyoffice/Tools/default-onlyoffice-ssl.sh
Place the created certificates to the /var/www/onlyoffice/Data/certs/
. There must be two files there:
/var/www/onlyoffice/Data/certs/onlyoffice.crt
/var/www/onlyoffice/Data/certs/onlyoffice.key
And run the script:
sudo bash /var/www/onlyoffice/Tools/default-onlyoffice-ssl.sh
It will do everything needed to switch your ONLYOFFICE Groups installation to HTTPS.