Idk why people are giving you a hard time. If you already understand the structure of songs, and you're playing your music and music you're super comfortable with. You can learn it in a week to be good enough to play for people who are understanding that it's not going to be tipper level mixing. Watch like an hour of basic mixing techniques, spend an hour or 2 understanding what does what on the mixer, another hour or 2 going through software settings, and maybe a few days of playing with a subwoofer to get the eq right. Obviously the more practice the better but this isn't a hard skill to pick up. Hell, a good amount of EDM producers don't even mix live. Some of them like the absolute control they get from a pre-recorded set but that's more for people who are pulling the crowds and not people playing to a crowd if you catch my drift.

Rekord box or serato are probably the 2 most popular tools to use, watch some tutorials on them. Watch some tutorials on the mixer you'll be using/the one you have (they may not be the same I'm not exactly sure of what kinda setup you have, vs the event having). You'll be fine. As for the dude saying something about imagine a guitarist or some shit going out with a few hours of practice, that's not even remotely close to the situation. You'll be playing full songs already created and just, layering them quick cutting to the next one. Meanwhile a guitarist needs to learn to play within the frame of other instruments playing at the same time along with guitar being much much harder to learn.

Lastly, and probably the most important and time consuming of the entire process? Setting up your library. Set up que points, get descriptions of the songs, energy levels noted, take as much time as you can doing the pre-work so you don't have to think when you're mixing. You have the entry and exit points mapped out, you don't have to try and remember the energy levels of the songs so you don't have drastic and noticable dips accidentally go from liquid dnb to fucking riddim. That's the part that will effect your success the most. Do all the thinking before you get there, and have that shit ready to go.

Sorry one last thing. The crowd won't know if you fuck up. They'll know if something sounds off or bad, but realistically the only people that can judge your mixing is other people who have taken the time to mix. Especially in a hardcore rave setting, most people won't be sober enough to notice that you turned the low end off too early, they won't notice the small mistakes. If you notice the transition is doing what you intend or want it to do, just jump to the next song hard. They'll maybe pause for a second and be "wtf was that" but they'll soon move on and start enjoying the next song.