Citation Generator builds a reference entry in all three major styles at once from the details you enter. It's a manual-entry tool, nothing is fetched from a URL automatically, since that would require sending the address to a server, which this site never does.
Pulling details from a URL automatically means fetching that page's content, which can only be done through a server, something this site deliberately doesn't have. Entering details manually keeps the tool fully private, with nothing about what you're citing ever leaving your browser.
APA 7 generally doesn't call for an access date on stable web content, so it's left out of the APA citation. For MLA and Chicago, the access date is only used when no publish date is available, since that's when those styles actually call for it.
No. Titles are used exactly as typed, since automatically deciding which words to capitalize risks mangling proper nouns and acronyms. Enter the title the way you want it to appear.
Each style has its own real rule for long author lists (APA lists up to 20 before switching to an ellipsis; MLA and Chicago switch to "et al." sooner), and this tool follows the common, simplified version of those rules rather than every edge case in the full style guides.