To qualify for any FOA Title recognized by FIDE, you need to play the FIDE Online Arena Rating and fulfill a number of conditions, after which you can claim the FOA Title.
Here are the conditions. Basically, you need to reach a certain rating and then don’t fall below that rating for a certain number of games (the actual number of games depends on the time control). Both single games and tournaments count towards your rating, and after each game, the rating is displayed along with a status of your Title progress.
To play FIDE Online Arena rated games and tournaments you need a subscription.
The "claim title" button will appear in your User Profile in the upper right corner and you will be able to get it as soon as you are eligible. The eligibility is counted automatically.