I found the following related tickets: could be helpful to troubleshoot your connection issue.
Incorrect JAR File (Sources vs. Binary):
You uploaded ngdbc-2.24.8-sources.jar. The -sources JAR typically contains the source code for the library, not the compiled binary code that the JVM needs to run. You need the binary JAR file.
The correct name would usually be something like ngdbc.jar or ngdbc-2.24.8.jar (without -sources).
Action: Ensure you’ve downloaded the actual JDBC driver JAR (the compiled binary) from SAP’s support portal or Maven repository, not the sources or javadoc.