If you receive this error message:
"You are already a member of a MobileDay Business account. Please contact your team administrator to be added to the existing team." that message generally indicates that you have tried to log into the website with an incorrect password. To log into the website you need to enter the password exactly the way you created it in the MobileDay app originally. It needs to be entered identically and will be sensitive to an extra space after the password or lower case/upper case discrepancies.
In these cases it is often simplest to contact firstname.lastname@example.org where we can assign a temporary password which you can use to log into the app first and create a brand new password and then use that new password to log into the website as well.