There's another solution similar to Auth0 and Okta called FusionAuth.io that you might want to try. Easy to download and install without having to sign up for any plans or accounts.
Netlify is for hosting. It's not a CMS. And it is free, depending on the chosen plan.
There is Netlify CMS, though. It's open source and free to use.
https://docs.netlify.com/routing/headers/
https://www.netlify.com/blog/2017/02/23/better-living-through-caching/
These should get you started. Keep in mind you don’t want to get rid of all your cache, keep whatever isn’t changing much or at least don’t forget to change your headers after you finished most of the work on the site.
I don’t use react really, but I believe it’s similar to vue enough for this to work...when’s the last time you deleted your dist/build folder and npm folder? You should delete both and then run npm/yarn and then build it again. I’ve run into some similar problems that were just from all the npm gunk.