Can I buy FC24 Coins if the transfer market of my account is not open on Web APP?
Unfortunately not, ALL coins delivery is made on Web App, not only on our website, it works the same way on any other coins store. You can get the market open by playing games though.
HOW TO UNLOCK TRANSFER MARKET IN FUT:
Play 3 full matches in UT Mode and log into Web App or Companion APP within a calendar day. Normally, keep playing 2 active days would get unlocked. But you share your device with your friends who also play FC24 games, it may take 4 active days or more days. So it depends on the number of accounts used on a device.
You can watch the Video to learn about it: https://www.youtube.com/watch?v=oEqjFhEO32U
With your second account, on the other hand, a little more diligence and discipline is required, because here it often takes about 7-10 days and 20-25 Ultimate Team games until you have unlocked the transfer market on the Web App.