Struggling to clear Advents is normal as a new player. It's a tough life when you're still weak. Raid events are far more newbie friendly since others can kill stuff for you.
Also, yes, you should use SR Cybele. You should pretty much never run more than one off-element Hime.About 1% per 10-roll, so you have a coin-flip chance at around ~1300 dollars and 90% chance at ~4400 dollars.
Non-miracle ticket Gachas are basically scams, as you can see.