You can definitely still use all the free features of Roll20 for a Star Wars campaign, but using the dice/character sheets in Roll20 require a subscription since they alter the API or something to that effect. You can definitely get away with doing everything off of Discord with a dice roller and nothing else, but I prefer being able to have everything together. There really isn't a wrong way to do it though. More personal preference.

I'm a fan of Foundry VTT. It does cost $50 up front, but then the program is yours forever. The GM is also the only one who needs to buy the program as players connect from a link you setup in your browser. Some really talented programmers have added this system to Foundry and are continuously updating it. It has it's issues, but I like GMing on it a lot more than I do on Roll20. Like others have also said, using Roll20 to play Star Wars requires a monthly subscription. I don't remember if it was the $5 or $10 a month that was required, but if you think your campaign will last a year or if you're going to ever GM again, Foundry would be a good investment. Foundry also allows you to import a lot of things from Oggdude's character generator and the Star Wars Adversaries website. That alone makes setting up games so much nicer. Foundry also went on sale around Black Friday and perhaps it will again around Christmas. Who knows? Good luck and happy gaming!