You do not have permission to use the bulk load statement error

ALTER SERVER ROLE [bulkadmin] ADD MEMBER [user]

To make sure you have the right permissions to use BULK commands follow the below

• Expand Security
• Expand Logins
• Right click on your username and choose properties (A dialog window appears)
• Choose Server Roles
• Select bulkadmin to be able to use bulk commands or sysadmin to be able to use any commands to your database.

Now, in regards to the query your are using it's not quite right.

For creating the table

CREATE TABLE [dbo].[Stickers] (
        [name] varchar(10)
        , [category] varchar(10)
        , [gender] varchar(1)
        , [imageData] varchar(max)
)

For inserting the large value data

INSERT INTO  [dbo].[Stickers] ([name], [category], [gender], [imageData])
SELECT 'Red dress'
        , 'Dress'
        , 'F'
        , photo.*
FROM OPENROWSET(BULK 'C:\Users\username\Desktop\misc-flower-png-55d7744aca416.png', SINGLE_BLOB) [photo]

A couple of notes:

• You need to set a correlation name for the bulk rowset after the FROM clause ([photo])
• Use the right column prefix that has been used for the correlation of the bulk rowset (photo.*)
• The column for the bulk insert needs to be set as varchar(max)

MSDN article for this: here

Possibly one needs

ALTER ROLE [sysadmin] ADD MEMBER [user]

For example - in the current Linux version of SQL Server bulkadmin role is not supported and one needs to use a sysadmin to BULK INSERT. It is a known issue with SQL Server https://github.com/MicrosoftDocs/sql-docs/issues/4198 - SQL Server on Linux has permissions and roles that are not granular enough.