Follow the below mentioned steps to link your eBay seller account to eBay Professional Importer app.
Step 1: Login to your Shopify store admin and click on the left menu: Apps.
Step 2: Click on the app eBay Professional Importer as shown in the below screenshot.
Step 3: Now you will see the app’s dashboard. Go for the option: eBay Account.
Step 4: Choose the eBay site belongs to your eBay account and click on the button CLICK HERE TO CONNECT EBAY ACCOUNT.
Step 5: You will be redirected to eBay website for your authorization to connect your eBay account with the app. Enter your eBay login details and click on Sign in button.
Step 6: Now click on Agree button as shown below to accept the permissions.
You will be redirected back to the app's dashboard once this process of connecting eBay seller account gets completed.