Hello @cirop68, welcome aboard to the Fitbit Community! I would like to clarify is the issue at the moment to log in is with your computer or the Mobile app?
If is with your mobile app, some of the times it’s usually because you set the time manually on your Android device. You can correct this issue by going to Settings > Date and Time and turning on the "Automatic date and time" option. The time must be within one to two minutes of the correct time to log into the Fitbit app.
In other instances, changing the password from your online Dashboard might help to resolved the logging error on your app. Try to change the password regardless if the information you are using is correct.
If the issue keep persisting please review the following post, it might be a similar case.
Keep me posted how it goes!
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