It looks like there is already the user named ODBC within the database.
Probably it has been created earlier for some purpose.

Have you already used ODBC with Projetex? Probably, with the older version of Projetex?
Is it possible that ODBC user has been created manually?

In case you do not need ODBC login within your Projetex 3D database for other applications, you might want to remove the SQL corresponding login using some third-party SQL tool (or first-party one like SSMS) and then try to enable the ODBC switch again in Projetex.
Please see https://social.msdn.microsoft.com/Forums/sqlserver/en-US/0eb79769-c0c5-4fba-aca9-9ffaa30a3361/the-server-principal-username-already-exists-microsoft-sql-server-error-15025?forum=sqlsecurity for details.