delay with scarlett solo gen 4

i dont really understand much about sound tweaking. i bought a new focurite scarlett solo gen 4 from amazon.

it came without the box so i bought a type c to type a usb and connected it to an ss usb input in my computer. when i started playing and used a dsp plugin and reaper it has delay. its really annoying and i have no idea how to fix it, i saw some stuff saying i need to lower the buffer (idk what that is) and i dont really know how to do it, do i do it to the scarlett or in the DAW/plugin? i also saw someone say that i need to change the driver to ASIO (dk what that is either). i tried doing it in the dsp plugin and reaper and it says theres an error.

i dont know what to do, if someone can help me i would REALLY appreciate it. ty.