Start problem - imfile, rsyslog - rpm CentOS 7

I can not start api-umbrella on CentOS 7 (binnary rpm installation by https://apiumbrella.io/install).

Status of service is:

$ systemctl status api-umbrella.service
● api-umbrella.service - API Umbrella
Loaded: loaded (/etc/systemd/system/api-umbrella.service; enabled; vendor preset: disabled)
Active: inactive (dead) since Tue 2020-01-07 11:40:12 CET; 1s ago
Process: 31023 ExecStop=/etc/init.d/api-umbrella stop (code=exited, status=0/SUCCESS)
Process: 30943 ExecStart=/etc/init.d/api-umbrella start (code=exited, status=0/SUCCESS)
Main PID: 30943 (code=exited, status=0/SUCCESS)

Jan 07 11:40:11 api systemd[1]: Started API Umbrella.
Jan 07 11:40:11 api api-umbrella[30943]: Starting api-umbrella: [ OK ]
Jan 07 11:40:11 api rsyslogd[31039]: imfile: no files configured to be monitored - no input will be gathered [v8.1904.0 try https://www.rsyslog.com/e/2212 ]
Jan 07 11:40:11 api rsyslogd[31039]: [origin software="rsyslogd" swVersion="8.1904.0" x-pid="31039" x-info="https://www.rsyslog.com"] start
Jan 07 11:40:12 api rsyslogd[31039]: [origin software="rsyslogd" swVersion="8.1904.0" x-pid="31039" x-info="https://www.rsyslog.com"] exiting on signal 15.
Jan 07 11:40:12 api api-umbrella[31023]: Stopping api-umbrella: [ OK ]

in /var/log/api-unbrella/rsyslog/current is same error message:

rsyslogd: imfile: no files configured to be monitored - no input will be gathered [v8.1904.0 try https://www.rsyslog.com/e/2212 ]

What can I do?

Thanks

Start with /etc/systemd/system/api-umbrella.service and /etc/init.d/api-umbrella, then inspect the reported rsyslog output in /var/log/api-unbrella/rsyslog/current. Reproduce the CentOS 7 startup behavior and determine why the service becomes inactive; done means the service remains active without the reported imfile error.