Following the update to 20.2, the process for managing one’s subscription in-app no longer goes by this outlined process as a result of updates to the UI. Infinite Flight checks whether or not you have an already active subscription on said device, and if so, it will not display the “Get Pro” option, which isn’t the case for the OP.
In following Tyler’s video here, as well as the updated support website documentation, you should log-in via Google, Facebook, or the Forum for a quick authentication first before linking your IFC. @Felix_Monroe since you still have “Get Pro” showing in your screenshot, it seems that you haven’t signed into your active subscription yet.
However, that said, seeing as you’ve already tried to log-in by tapping on “Get Pro,” and “I already have an account,” and then signing in through Google to no avail, it suggests that Infinite Flight was unable to authenticate your account with your Google log-in method.
My recommendation is to email support at email@example.com, and provide them with your callsign information (no display name, since that was removed from the game in 20.2), your device, and complete purchase receipt.