The linked post doesn't explain it well actually.
First of all, enter an offline Lobby. Then go back to main menu and try to enter an online one. Select region etc and when the screen goes black with the loading icon on the bottom, it's the time to disconnect your internet. You should pop both trophies as soon as you're disconnected, if you haven't already. You can then check your money in offline mode. Rinse and repeat, stonks.
You need to enter an offline lobby first or else you'll trigger the reward window as soon as you enter the offline lobby, and will prevent it from triggering again in the current day. I did many testings and got this to work consistently with the above instructions. I believe you can farm 15 million in just under 2 hours using the daily bonus, and in 5 minutes with the 5 million one.