Yep, get a booster if possible and get a good squad for index. I use inaros and a heavy radiation build on a vaykor hek.. magnetism on primary and viral on melee is key.

The reason I find it hard is because I tried the one for Glast gambit and it was hard

Don't compare. Your friend is literally a bot, and nef is practically cheating.

If you have a decent weapon for index, bring a tanky frame. I recommend wukong, as you get 3 extra lives that dont force you to drop points, and his cloud form is good for getting to the goal quickly. Another option is to play gara. Build up damage on your glass armor and you will both be hard to kill, and kill everything just by touching them. Also you can set up a wall at the enemy goal post

Just keep grinding but also selling stuff you dont need or have double

Index on Neptune

Index or profit taker drop loads of credits