We allĀ“ve been there.
There are few points in the game where the difficulty ramps up and forces you to take some time grinding missions that you can run reliably without loosing any tanks in the process.
Its harsh to be a new player during events, since those tend to be harder than usual maps (admittedly this one is the easiest so far - no special super strong turrets, no boss with multiple abilities, no ravager or wraith or whatstheirname spam).
You just have to bite the bullet, focus on lvling and getting those stat boosts from increasing relationship with your tanks.
Also upgrade your Emblems of 3* and higher quality. The 3* emblems give already pretty solid buff to their stats. Not all are worth it, but if you get some that have good secondary skill setup (Lets say you have a HP emblem, and the secondary skills are Evasion, more HP and DMG reduction - thats a great defensive emblem you want to upgrade and stick onto your main Tank....tanik ).