am solo player i soloed part 1 and 2 and died alot but the rest gonna be hard to solo, i cant find anyone to help with the quest

Barrier of Infestation has been already converted to solo content. No one can help you anyway, except maybe a friend/guildie shai that could buff you up while not in your party.

Only a guildmate can buff you while you try to kill him

Yet if you simply aren't strong enough to finish Kzarka... you are simply not strong enough.

Try again when you got better gear or got better at your class

I couldn't beat him at first, I was way, way too weak and inexperienced with my class. After months of dedication I was able to go back and beat him in one attempt using a shai. It wasn't terrible. Church buff, food buff, perilas star and tent buff was more than enough. I didn't even have good crystals either. I had maybe 15-30 seconds to spare. Mind you that shai isn't an overly OP PvE class. My advice is learn how to evade and use your invulnarbility and invisincibility skills.

In other words, the two things that will help you here is 1. Get better equipment and 2. git gud.

The difficulty level of this boss is intended to prepare you for elvia and more difficult content in the game. Treat it like a test of skills. If you can do it then you are good enough to move on to the next stage in the game.

Get a shai or witch friend in the same guild as you and have them heal and buff you. You dont have to be in a party to get the heals and buffs and it makes a big difference.