If you're not able to publish a content on your Google Business Profile, probably your user doesn't have permission to post to this location.
Please check your location in Google my business page (https://business.google.com):
1) Log in to the account you have connected to RADAAR
2) Go to Manage Locations via left panel.
3) Click on the location you are trying to publish your post.
4) Do you see the option Create Post?
If you don't see the Create Post option, please change your Google My Business settings/privileges to allow to create posts. You can publish with the following roles: Primary owner, owner, manager or Communications manager. Then reconnect your Google Business Profile to RADAAR and try to publish a content again.