Arcanist to 60 ?

Simple question cause i'm really new to this game and i was wondering do i have to choose a Job at 30 or i can lvl arcanist up to 60 , what's the advantage of choosing a Job insteat of lvl a basic class

Tkx for ur help

The reason to do a job is simply because ifnyou desire to be a DPs as a summoner which comes off of acanist as a job you gain alot of great job only attacks. If you desire to heal you can not as an acanist but if you take the job scholar which comes off of acanist it has all of your heals.
As a rule I have seen people who only roll a class past 30 kicked from instances as you will be missing the majority of your skills to get your damage or heals on par with other players using their jobs.

Forgot to mention acanist levels up while you have your job crystal on, the beautiful thing about playing arcanist is to heal as scholar they will be the same level you just have to do the job quests from 30 to 60

Think of a job as a promotion for your class. You get all of the skills the job offers (by completing job quests) plus the skills you already have. On top of that you get a sizeable bonus to your primary stat. There's really no reason to not equip a job stone at 30+

The jobs are basically advanced classes. You "equip" a job by equipping the weapon for the base class and adding on a job soul crystal - that empty lower right slot in your equipment. All xp earned with a soul crystal equipped goes to the base class.
Your class quests that you have hopefully been doing every 5 levels stop at 30. After that you are expected to do the job quests instead.
Each class has only 1 job available for it EXCEPT arcanist. Arcanist can go to summoner (dps) or scholar (healer). You don't have to choose only one. Just as you can level every class, you can have a crystal for every job. Most arcanists specialize in either summoner or scholar just because of where they want to put their bonus stat points. I mainly use summoner but also keep scholar geared.
The job crystal, aside from giving you access to the job skills, gives you a big stat boost too.

The only disadvantage to having a job crystal equipped is that it limits your cross-class skills. For example: if you had leveled conjurer up to 44 for stoneskin you could cross-class that to use as arcanist but not as summoner. If you are running level appropriate dungeons this tends to not matter. If you are running lower level dungeons (<30) some people will take off the job crystal for more cross-class skills.

In terms of dealing with other players, there is some leeway but most people will expect you to have the job crystal by level 35. As summoner that is when you get one of their high damage abilities. And, if you want to heal, you have to have scholar equipped to enter a dungeon in a healer role.
If you aren't sure if you want to dps or heal, unlock both jobs at 30 and test them out.