Problems with jetways doesn't obviously have anything to do with GSX, especially considering you are reporting a problem with a 3rd party jetway in a 3rd party scenery.
Also, Jetways in MSFS dock where they want, but the correct door is 2L, so GSX asks you to open that one, because that's how has been configured in the GSX profile as preferred exit so, either park in a position where 2L solves instead of 1L or change the preferred exit to be 1L, if you prefer using that one.
Integration like the 737 will come in a future update.