If you're using exact and have multiple companies configured in exact but want Shiptheory to work for just one of the companies, you'll need add the target company's id in the advanced settings from the Shiptheory Exact settings page.
To access the Exact settings in Shiptheory, click your email address on the top right of the screen, and select Exact from the drop down list:
You can access the advanced settings, by clicking cog at the bottom of the page
To get your target company id (division id), in Exact, navigate to the Company > Settings page.
Look at the URL in the address bar of your browser and you should see something like this :
Take this number and enter it in the Shiptheory settings page, and hit save.