I apologize in advance for this question but I have never dealt with midi cables before.So far I only used usb to connect my keyboard.
I want to get the Fatar studio 900 keyboard from someone.It's pretty old so It doesn't support usb but I like that it is fully weighted.It only has midi outputs.
What is my best option for connecting it to my computer and using it in my DAW ?
My audio interface is an EMU tracker pre and doesn't have any midi inputs.Is getting a midi to usb converter cable and connecting it to my pc good enough to get good response (no delay) or is it a must to get an audio interface which supports midi ?

Any decent USB Midi device should work. USB is faster than Midi when it comes to transmission times, so you shouldn't see any noticeable delay (in theory).

I've never tried it, so I don't know. I've only used Midi over USB when built into devices or the Midi built into my audio hardware.

Thanks for the answer ! I hope that I won't gave delay problems.

There won't be any delay. I use a Casio digital piano with midi into my Axiom Pro keyboard, which functions as a midi to usb interface. There's no latency at all.

Human fingers are slow, MIDI protocol is fast enough.