HTTP access (auto-provisioning) is found in:

/opt/pbxware/pw/var/log/nginx/localhost.access_log

HTTPS access (PBXware Web interface) is found in:

/opt/pbxware/pw/var/log/nginx/localhost.ssl_access_log

These files can be viewed with the command less or cat, for example:

less /opt/pbxware/pw/var/log/nginx/localhost.access_log