Samsung Galaxy Z flip5

Pagar Desbloqueo de dispositivos de T-Mobile | Asistencia de T-Mobile to see how to check your device unlock elibility on your T-Mobile account. 

You may need to do a software update since you are getting Code 89. We see that code mentioned a lot on the forums, but T-Mobile doesn't return any codes like that during the unlock process, so I'm really not sure exactly what it means. If there is something preventing the phone from being eligible, you'll find that pretty easily in the steps on the website I linked above. 

Hope this helps!