There are a few ways to onboard data into Splunk.
Install a universal forwarder on the server to send log files to Splunk
Have the server send syslog data to Splunk via a syslog server or Splunk Connect for Syslog
Use the server's API to extract data for indexing
Use Splunk DB Connect to pull data from the server's SQL database.
Have the application send data directly to Splunk using HTTP Event Collector (HEC).
If this reply helps you, Karma would be appreciated.