I have a Marshall Valvestate 8040 from 1995. Is it possible to use it as a speaker for Garageband, connecting this amp to my Focusrite Scarlett Solo?

Hi everyone!
im a Marshall code 50 owner.

i was trying to record my guitar via USB using GarageBand, but it was not possible.

I setup the input as Code in GarageBand but doesn't work.

any suggestions? or maybe Code doesnt work with GarageBand?
can you recomend any interface (not an expensive one) to record my guitar?