Can't create table or database in sql server as permission denied in database master. Log in authentication is Windows authentication (./SQLEXPRESS)
In order to create a database, you need to either be a part of the
dbcreator fixed server role, or have either of the following permissions on the server:
CREATE ANY DATABASE, or
ALTER ANY DATABASE.
The fact that you are using Windows Auth is a neutral point, as within SQL Server it is a principal that still needs the required permissions to perform the necessary actions.