The eBay LINK Shopify app is currently waiting on Shopify to approve the new listing in the new Shopify App store.
While we wait, you can still install eBay LINK from here: https://ebaylink.omnivore.com.au/shopify/install
Enter your Shopify Store URL e.g https://example-store-name.myshopify.com
If you're not already logged into Shopify, you will be prompted to login then asked to install the app:
Click 'Install app'
You can then proceed through the set up flow.