The order shows " Transfer Market Locked", what should I do?

If your account is not locked, then it's not open because it's new. You can get the Web App transfer market open by playing games.

Here's how you can do it:

Play 6 matches daily, finish the first two daily objectives(Play 2 Matches, Win 1 Matches), get the season progress, objectives, milestones, and foundations task rewards, open all the packs you get, and keep playing like this for 5-6 Days, you will gain access to the Transfer Market on FUT Web App.

Please remember, this is the way how most players get their market open, but not work for everyone 100%, cuz the efforts you need to make to get it open differ, depending on the current situation of your account.

It takes some effort to get the market open on the web app, but playing games is the only way to get it open and buy coins, it works the same way in any other coins store. Let us know if you need any help.