The issues with buying Coins on Steam should be fixed now. If you're still having any trouble please give us a shout.
Were you logging into the game through Origin to check for those coins as well, or are you launching from Steam?
If you haven't already, try launching Apex from Origin to see if those show up for you then.
If you're still not seeing them, the system may be just doing a bit of catch-up from earlier. If that takes more than 24 hours to appear in-game, just reach out to an advisor and they'll be able to make sure you get those coins.