Hey @Nijjy ,
happy to have a look at this with you. Can I please ask for a screenshot of the email that you have received here so I can try to find more information about this and provide you with the right steps?
You can add this using the Insert Photos feature available (camera icon).
When I click on the link, select a Boost it tells you to sign in, you sign in and it says sign in you sign in and it tells you to sign in and you get nowhere!! I have tried this for all Boosts offered