Find your subdomain
Add the subdomain for your Sage account.
For example, if you sign in at "acme.sage.hr", add acme to Merge Link.
Do not enter the full "acme.sage.hr".

Find your API key
Log in and click on your name on the top right corner, and select Settings in the drop-down menu.

Click on Integrations in the left hand menu, and select API in the drop-down menu.

Copy the API key, and add it to Merge Link