Facebook policy states that third party apps, such as BOMA, cannot auto-fill the text for a post on their users behalf. This is because spammers can use technologies like ours to create fake news posts.
You can type your own message in the Post Content box or copy & paste from the content template which will insert the text you've already defined for your campaign.
Further Reading:
Link and image Previews on Social Media (Open Graph Tags)
How do I create a Facebook post?
How do I delete a draft campaign?
How do I create an email campaign in BOMA using my own content?
Can I share my blog posts on BOMA?
Can I share a link or article I have read online via BOMA?
How do I edit a scheduled campaign?
How do I stop or delete a scheduled campaign?
How do I create and share a lead capture form?
Create a Newsletter from the Dashboard
Where can I find the Accelerate Newsletter in BOMA?
Sharing your email as a social post
Creating Lead magnets and Lead Forms in BOMA
Stopping a live campaign in BOMA
What channels can I send a campaign to?
How do I create a campaign for email, Facebook, LinkedIn, Twitter with my own content?
How do I post to my social media channels - Facebook, LinkedIn, Twitter?
What channels can I use to send out Xero content?
What type of LinkedIn campaigns and posts can I send?
How do I review and send my email campaign?