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, 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 of players get their market open, but not works for everyone 100%, cuz the efforts you need to make to get it open differs, depends on the current situation of your account.

It takes some efforts to get the market open on 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.