When I try Splash by using Scrapy-Splash, it doesn't support navigating like a real browser. It only renders the HTML, but when it clicks a button, it doesn't render the next page it navigates to.
From my simple research, web scraping with navigation is only supported by CasperJS. But, is it possible to combine Scrapy and CasperJS
You're confusing browser with testing frameworks, Selenium does exactly that but instead of Firefox, use PhantomJS as a headless browser (which is what CasperJS uses).
# Assume the button has the ID "submit" :)
driver.find_element_by_id("submit").click()
alexce answer on scrapy with selenium
If you need the content of the requests, use something like BrowserMob as a proxy.