ClassNotFoundException error when using opencsv

I am a beginner java developer using Eclipse. I want to read in a CSV file and want to use opencsv utilities as a reader (and use other opencsv utilities when I get off the ground). I have downloaded the JAR (ver 5.8) and added it to my Build Configuration. I have addressed all compiler errors, but at runtime, I am getting a ClassNotFoundException for com.opencsv.bean.CsvToBeanBuilder. I have tried a previous opencsv version (5.7.1) but get the same results. I can see the com.opencsv.bean.CsvToBeanBuilder.class when I hunt through the files. Must be something simple I am missing? I have downloaded the JAR file only, no source or javadoc.

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.List;

import com.opencsv.bean.CsvToBeanBuilder;


public class RaceResultsParser_v2 {

    public static void main(String[] args) {

        String inputfile = "inputfile.csv";
    
        try {
            List<ClubMembers> memberlist_input = new CsvToBeanBuilder<ClubMembers>(new FileReader(inputfile)).withType(ClubMembers.class).build().parse();
        } catch (FileNotFoundException e) {

            System.out.println("An exception occurred while opening the CSV file [" + inputfile + "]: " + e.getMessage());
            System.out.println("File Not Found Exception");
            e.printStackTrace();
            return;
        }

Project Explorer

I have trolled stack overflow and the internet more broadly but can't seem to find my solution.

Console output from the program run:

Exception in thread "main" java.lang.NoClassDefFoundError: com/opencsv/bean/CsvToBeanBuilder
    at RaceResultsParser_v2.main(RaceResultsParser_v2.java:17)
Caused by: java.lang.ClassNotFoundException: com.opencsv.bean.CsvToBeanBuilder
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
    ... 1 more

When I add opencsv to the Run Configuration, a slightly different console error comes up referencing org.apache.commons.collections4.MultiValueMap:

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/collections4/MultiValuedMap
    at RaceResultsParser_v2.main(RaceResultsParser_v2.java:18)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.collections4.MultiValuedMap
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
    ... 1 more

Run Configuration