I have a table on an existing SQL Server 2014 database as follows:

CREATE TABLE [dbo].[Files](
  [Id] [int] IDENTITY(1,1) NOT NULL,
  [Content] [varbinary](max) NULL,
  [Created] [datetime2](7) NOT NULL,
  [Flag] [nvarchar](100) NULL,
  [Key] [uniqueidentifier] NOT NULL,
  [MimeType] [nvarchar](400) NOT NULL,
  [Name] [nvarchar](400) NULL,
  [Pack] [uniqueidentifier] NOT NULL,
  [Slug] [nvarchar](400) NULL,
  [Updated] [datetime2](7) NOT NULL,
CONSTRAINT [PK_File] PRIMARY KEY CLUSTERED 
(
  [Id] ASC
) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

What is TEXTIMAGE_ON and why not just [PRIMARY]?

How can I change this table to use FileStream? So it would have:

[Key] uniqueidentifier rowguidcol not null
    constraint DF_File_Key default newid()
    constraint UQ_File_Key unique ([Key]),

And

) filestream_on ???

UPDATE

I have the following TSQL:

exec sp_configure filestream_access_level, 2
reconfigure

alter table dbo.Files 
    set (filestream_on = 'default')

alter table dbo.Files
    alter column [Key] add rowguidcol;

alter table dbo.Files
   alter column Content filestream;

alter table dbo.Files
   add constraint DF__File__Content default (0x),
       constraint DF__File__Key default newid(),
       constraint UQ__File__Key unique ([Key]); 

go

But when I run it I get the error: Incorrect syntax for definition of the 'TABLE' constraint.

I am using "default" because I want to use the default filegroup.

What am I missing?