First gig

I wouldn’t have a clue where you would get your hands on those types of tunes but I will say that you have to make peace with sacrificing your musical integrity (just a bit) to get those first few vital gigs. Either that or show up every night and spend a lot of cash shouting the important people drinks.
I’m sure you could google “Reggae classics” or “Soca top 50” or something like that to help with songs.

Also, and this isn’t meant to scare you, but be prepared that “play whatever you want” actually means “keep on playing what you were playing at the start of the night”. Basically, really stock up on your top 40 so you have lots to fall back on if it isn’t working out quite as expected. Good luck!

As Oddity says: Be prepared to play all night long Top40 etc. if the crowd stays in or you will wipe the dancefloor clean.
The whole raggae, soca etc. deal is actually quite fun and easy to mix, just practice a bit to downmix a fast Top40 song into a slow chill raggae. As raggae has a very distinctive beat line that is quite different from most other stuff you can easily try to cutdown a loop at the raggae intro depending on your software cut this loop in double time and crossmix it with the faster tune, where you cut the bass EQ and fade over.
You can also look up several youtube videos on how to mix from a fast to a slow tune, I think DJ Iceman has a good example on his feed and there are several others.

But the biggest thing is: PREPARE your songs, know your cue points and where to loop for blending. When in doubt try to cutover a mistake by a heavy flanger and practice making mistakes.
Just remember: Never stop, never surrender. Mistakes happen, just make the best of it and don’t freeze up and you will be fine.