I just rolled 15000 crystals because of the legfest that started today and didn't get an SSR anything. I'm curious as to what I should do now since I'm at a point in the story where I can't progress (Chapter 48) because I can't beat the guy without spending full elixirs which I don't have anymore of. What should I be doing at this point in the game to get stronger?
Also how can I get more crystals now that I've spent all of mine?
I've done all the side missions that I could on all the islands so I'm not really sure on how I can roll for legends again without dropping $30 (I don't plan on spending more than a dollar on this game)
To get stronger, you should do Celeste Magna and hope for SSR weapon drops (assuming your main team is dark). Also, do the story bosses for renown pendants to trade for SSR magna weapons. To get more crystals, you can do co-op quests if you haven't done so already. Or just wait for events to roll by. You can also get crystals from achievements, but you'll get them naturally as you play through the game so you don't need really to aim for any in particular. If you don't plan on spending money, only way to roll is with crystals, or tickets (which you get from various events, daily logins and collaboration campaigns).
Start doing weekly dungeons, gather evo mats, do your low lvl magna raids. Try to get all the mats you can get and start evo'ing people and collecting SR magna weapons for beginners.
You also need to start doing events and gather your proofs or pages to do your final evos for your characters and possibly some decent SSR power ups. I also suggest you review the Ultimate Guide to see if there is anything else you may want to aim towards.
Maybe you're focusing too much on the story...? I'm at chapter 28 and my total atk is 11.311, 8132 it's pretty low if you're that far up. Events gives you 3x SR weapons that you can fully uncap to lvl 75, as a start is really good, if you get bored on doing Magnas (And they get a huge nerf if you're not lvl 50+), of course.