Log in to Strava first. Strava uses OAuth2 as an authentication protocol. It allows external applications like Flow2Strava to request authorization to a user's private data without requiring their Strava username and password. It allows users to grant and revoke API access on a per-application basis and keeps users' authentication details safe.
Enter your username and password to retrieve your last week of Polar Flow training files. Polar does not allow me to use their AccessLink API. Therefore I used a workaround made by grzeg1. Your username and password are salted and encrypted before saving, but I cannot do otherwise than send them unencrypted via POST request to Polar to authenticate. Your username and password are removed as soon as you logout from Polar Flow in this application.
Click on the upload button and enter a title for your activity. Only one click left and your training will be shared on Strava!