My advice- if you can do a single pull up or even half of one, then that should be your primary way of training. Do 4 sets of 1 (or even 1/2 or 1/4) every day, it will help you way more than the assist machine. If you can’t do any pull ups, no worries, work on the assisted machine, but make sure you do deadhangs every day for as long as you can. Your body needs to get used to holding its own weight. You got this!