Internal and External Links
To access external links from the results in the Research tab, and also to see Internal Links suggested based on your site's Google Search Console data, open a Frase document and click the "Links" tab.
External links
For external links, you can filter by domain where the external links are going to (screenshot below). Clicking the domain will show a block of text where the external link resides, and the anchor text (text that actually holds the link) is underlined.
Internal links
If you have already integrated your Google Search Console (GSC), you'll be prompted to do so when clicking the "Internal Link" text at the top. The integration will occur outside of the document, and once completed, you can open the doc again and navigate back to "Internal Links" section where you'll see the domains from GSC you can select.
After clicking a domain, you can delete topics that may appear automatically and can add your own by typing in the text field and pressing return. Then, click the "Refresh data" button to search for internal links on your domain via GSC, and links will be brought up if found (screenshot below for "SEO strategy" topic).