@kuvshinoviFirstly, please understand that disabling the system integrity protection is NOT something you should be doing lightly. You also do not need to do it to download and install the game, and you definitely don't need to have Origin in-game enabled at all to play.
I'm not sure what is going wrong with your installation but we can try a few things to try and fix it:
1. Run the Origin reset tool -
https://help.ea.com/en-gb/help/origin/origin/how-to-reset-origin-on-mac/2. Re-enable the system integrity protection on your Mac
3. Try to buy a pack through the Origin app or through the Origin website, not through the game.