Hi, @omarfaridi1987
For the first question, it is normal to have red error messages after you shutdown the test script. If you have confirmed that the testing is passed, then it is ok.
For the second question, it seems that there is another process using the port gtp needed. So make sure the port is available, you can use command
lsof -i :<port> to find out.
Hope this can help you.
BTW, this is free5GC neither 5GFREE nor 5Gfreecore XD