These types of immobilizer interfaces are to use for remote start setups, you don't need this if you just want to use "regular keys"
These shouldn't let anyone use a regular key to start engine, that would means PATS was disabled and thats not what these are made for.
For remote start system when you open the door or touch the brake pedal the remote started engine should shutdown, and won't restart without working PATS key in the ignition.
This prevents a thief from driving off your vehicle as it warms up
To do what you want, get a Regular key cut/made, then remove the steering column cowl , 2 or 3 screws
You will see the Transceiver ring around the key slot, looks like this:
https://i.ebayimg.com/images/g/NZkAAOSwjVVVppqL/s-l300.jpg
This is what "reads" your PATS keys number when you turn on the key
Tape your PATS key next to the ring
Try to start engine with "regular key"
If THEFT light flashes rapidly it can't read the PATS key, try a different location for the key
Once it can read the PATS key each time regular key is turned on secure PATS key at that location and put cowling back on
Worst case is you have to remove the transceiver ring and move it down under the dash and tape the PATS key inside it so it can be read everytime
Alternative is to have your working PATS key Cloned, locksmith can cut key and Clone/Copy the same number on to a New PATS key, so you have a working spare key, at a lower cost than having new PATS keys added to PATS memory
Just FYI, this is what the 3rd party Remote start setups do, they "read" the key number during installation and setup, then they use that number during Remote start, so an electronic Clone of your current PATS key