Hello, I am brand new to this mod. I have done a fresh install and everything loads fine. however I am having an issue arresting people. I have held E and nothing happens. Its starting to get frustrating and I was hoping someone could help me.

Do you only have LSPDFR installed or do you have Stop the Ped also.  If you have Stop the Ped then you would have to disable lspdfr's arrest function.  I have Stop the Ped and it works for me.  Get close to the Ped and maybe double tap E.  Either hold E or press E twice.  Then you should hear your Officer character say something like "Stop right there".  To test, go up to ped that is standing, not walking.  get face to face and press E or hold E or double tap E to get the Peds attention.  Then press E once and a menu should pop up.   One of those should work.