The ACP API lacks SSL certificate domain and SSL port so cannot automatically construct the (preferable) https:// URL to the scheduler engine log if ACP has SSL running. This will require an ACP API addition. See ACP-1668
In the meantime, see
SCHEDULER-1667 for the change that allows a full https://domain:port/ to be put in the ACP Sequencer's Web URL Base setting, and used for emails if set in the configuration.