How to run a .jar file in Eclipse with JUnit 5

I am working on java projects for school, each one of them has a .jar file with a list of tests to test the project. I followed my professor instructions here http://ift.tt/2DeDUqa but I get an error like this No tests found with test runner JUnit 5. I am worried that my professor guide is too old for my Eclipse, I run Oxygen.

I added the .jar to the file then to the 'Build Path' and then I added the JUnit 5 library, instead of the file in the guide because I wasn't able to find the correct file, to the path but the error appears...

Am I doing something wrong?