You must make a purchase of Cartel Coins with a valid credit card or debit card before you can enable a payment method for Cartel Coin purchases in the game. This is what I see when I try to turn on in-game cartel market even though I made a purchase using my credit card. What can I do about it? Edited July 21, 2018 by Xidolo

As long as you have cartel coins you can use the cartel market.

 

What you're trying to turn on is the ability to buy cartel coins directly ingame without any further authorisation.

For this to work you need to activate it here: https://account.swtor.com/user/cartelcoins. If you just purchased cartel coins on the site for the first time, there may be a waiting time before you can activate this or purchase anything else, to prevent fraud.

 

The function is a little bit of convenience and a controllable risk (just don't give your swtor password to any kids, siblings, angry spouses or nigerian princes), but even if the 500-600 cartel coins a sub gets each month aren't enough, you can get better deals on 3rd party sites, like the Amazon and Origin bundles that include a big bunch of extra cartel coins with a 90 / 60 days gametime code.

Edited July 21, 2018 by Mubrak