Hi @dk2,
Welcome to the Bunnings Workshop community, it is fantastic to have you with us.
The best way to get a good colour match would be to chip off a bit of the paint so you can take it in-store with you. You could use a utility knife to cut and remove a chip of paint around the size of a 50-cent piece, then take it in store to be colour-matched. You would be repairing the patch anyway, so I wouldn't worry too much.
Alternatively, it may seem a bit silly, but you could always take the door off the hinges and bring it with you to be colour-matched.
If you took a chip off the door, fill it with some Selleys Spakfilla Rapid Gap Filler.
Once colour matched, you would make sure the patch is sanded smooth with a sanding sponge, then apply some primer before going over with a coat of your colour-matched paint
The texture you are seeing is just from a roller being used. Generally, doors are painted with short nap rollers like this 4mm Nap Little Ripper Microfibre Mini Roller.
Have a read of What is the best way to paint a door for some further guidance.
Jacob
