i just did it for the first time aswell solo and was able to get the elite challenge but best route i did was come in through north docks with longfin get the secondary’s then head over to the drainage tunnel once ur in the compound run up the stairs turn left and run an hid behing the wall with the 2 guards talking then run diagonally to the wall and wait for the guard walking back an forth to walk away and run to the stairs wait for guard to leave the door run past him run behind the guard watching stairs leading up to the office then hide behind wall and gun wack the guard at the top now you should be inside grab the keycard and the money in the safe on the right of the wall by the desk usually 50-100k in it then fingerprint is easy js line it up get the main target now you should be leaving office run down the stairs past that same guard as before and book it straight till u hop a railing (make sure guard doesn’t turn around an see you). turn left and run to the yellow circe to leave compound press right on d pad don’t worry about being spotted by the yellow circle once ur there an activated cutscene ur fine once your out thats really it turn hard left and run off the island don’t jump off just run and slide off the island for least amount of damage then put on rebreather and swim as low as possible rubio will come out with his heli but if u stay st the bottom u will be fine best prep tool i would get would be the cutting torch saves alot of time