Hello olaormani,
Thank you for posting in the Apple Support Communities and for reviewing the related article, Use Messages on your Mac. We'd like to offer our support.
First, check to be sure iMessage is set up correctly on your Mac.
Set up Messages on Mac
Also, ensure that Text Message Forwarding is enabled.
How to forward SMS/MMS text messages from your iPhone to your iPad, iPod touch or Mac
From there, make sure you're signed in to the same Apple ID for each device.
Sign in with your Apple ID
If this concern continues after taking the steps above, our resolution is to contact Apple Support directly. Depending on your region, you may be able to reach them here:
Get Support
We hope this information is useful. Kind regards.