Click on Channels -> Add New Channel menu at the left menu bar.
Select the type Etsy from the left tabs as shown below.
Click on the button Click Here To Connect.
You will be redirected to Etsy website for your authorization to connect your Etsy account. Enter your Etsy login details and click on Sign in button.
Now click on Agree button as shown below to accept the permissions.
You will be redirected back to the SKUBubble once this process of connecting Etsy seller account gets completed.