Assisted apply writes a tailored resume and cover letter from your Source of You record, with every claim checked against what your record supports. Applying always happens on the company's own page.
The posting, in Arista Networks's own words
Arista Networks's board does not publish the posting text in its listing API, so we can't show it here. Everything above is what the board publishes; the full description lives on the company's own posting ↗.