Your browser's print dialog does the export. Two settings matter:
Everything is read in your browser. The file is never uploaded anywhere.
Fastest — your profile as a PDF. Open your own LinkedIn profile, press More, choose Save to PDF, and drop the file above. It is instant, and the layout is read properly rather than guessed at.
More complete — your data archive. LinkedIn → Settings & Privacy → Data privacy → Get a copy of your data. Drop the .zip above when it arrives. Better data, but LinkedIn takes ten minutes to three days to send it. Only the profile files inside are opened.
There is no “connect to LinkedIn” button because no LinkedIn API gives out your positions or education. Nothing here signs in to anything.
Your CV, cut to LinkedIn’s fields and checked against the same rules. Copy each one and paste it into LinkedIn — no site can write to your profile for you.
Nothing here is rewritten for you. Inventing a number you did not give would be inventing a fact about your career.
Only mechanical changes. Nothing here invents content or changes what you claim.
Weak openers like “responsible for” and bullets with no numbers are deliberately left alone — fixing those properly needs you, not a rule.