Installed extension doesn't show up

I installed this extension on Chrome.

I want to uninstall it, but I can't seem to find it on the extensions page.
Note that in Chrome app market, the app shows the installation button as available, but when clicked I see this error:

I tried restarting Chrome but that didn't help.
Is there a way to remove the extension via Windows Explorer etc.

Solution 1:

Okey. I find solution.

1. If you login in Chrome -> logout.
2. Go to %LocalAppData%\Google\Chrome\User Data\Default\Extensions and delete extension folder
3. Go to %LocalAppData%\Google\Chrome\User Data\Default\Local Extension Settings and delete extension folder
4. Restart Chrome
5. Sign in
6. ...Done!

Solution 2:

Find a puzzle icon on the right side of already visible installed extensions (near ...). Click on it and a drop down of installed extensions is now displayed. Click on selected empty pins and it should work.

Image from this Google support questions

Solution 3:

1. Enter chrome://flags/ into your address bar
2. Change Enable Enhanced Bookmarks to disabled
3. Click Relaunch Chrome button at the bottom

You should now be able to install the extension again

Solution 4:

To extend @jazkat answer, since mid 2020 Google now hides application extensions by default, you now need to look for the puzzle icon

“Our goal with this new UI is to make it easier for users to see what extensions can access their data,” explained extensions developer advocate Simeon Vincent in a post to the Chromium extensions forum in May 2020.

“When the user clicks the puzzle piece icon, the extension menu opens and displays a list of all enabled extensions the user has installed. The extension list is grouped by the level of data access the extension has on the currently selected tab.”