Extension disabled after installing on Edge?

That's expected — Edge automatically disables extensions that override the new-tab page and search settings right after install, as a safety measure. Here's how to turn Pikamark back on:

  1. Open edge://extensions in a new tab
  2. Find Pikamark in the list
  3. Toggle it on
  4. If your new tab still isn't Pikamark, go to Settings → Start, home, and new tabs, and set "Open a specific page" to Pikamark, or reselect it under "New tabs"