GarageBand amp not working (iPad)

I recently bought a usb c audio interface compatible with my latest gen iPad Pro with the intention to use my iPad as a guitar amp. However when I plug my guitar into the audio interface and into my iPad, the amplifier in GarageBand does not change the tone of my guitar at all. My iPad is up to date and the firmware of the interface is also up to date (it is a presonus audio box go interface). When I go into the input jack icon in the top right, there is no monitor button which I have seen in other tutorials and I’m assuming it’s supposed to be there. As well as this the green dot that appears next to the icon seems to be picking up audio from possibly the iPads mic and not the guitar when I strum it. The only options I see in the input section is noise gate and input level. Any help would be appreciated thanks 🙏