You can enable the delivery log in the site configuration file, for example:
[deliveryLog]
enabled=1
name="log/delivery.log"
fileMode=0644
priority=6
The "name" path is relative to your Revive install "var" folder. So the log will go to, for example if Revive is at /var/www/revive_adserver to
/var/www/revive_adserver/var/log/delivery.log
You'll also need to make sure the folder exists and is writable by your webserver user, for example if the webserver user is www-data
mkdir /var/www/revive_adserver/var/log
chown www-data: /var/www/revive_adserver/var/log
After that the logs with the appropriate log level can be seen in delivery.log there.