Link Adder is built and run by one person, so your message is not going into a queue. It reaches the person who wrote the code.
Three things make a problem quick to fix: what you were doing, the exact wording of any message on screen, and your Chrome version, which is on the page at chrome://settings/help. A screenshot covers all three at once.
It is one person answering, so please allow a couple of days before chasing it.
Most reports turn out to be one of these four, and all four are fixable in under a minute.
Link Adder has no password of its own. It works out which account is yours from the Chrome profile you are already signed into, which is why there was never a sign-up step. If Chrome itself is signed out, there is no profile to read and the extension cannot tell who you are.
This shows up after an update when the permission prompt was closed rather than accepted. Reloading the extension brings the prompt back.
The extension talks to one server and no other. This message means the request did not arrive, so it is either the connection or the server. Open www.linkadder.com in an ordinary tab. If the site loads normally and the extension still says this, that is worth an email, because the two should not disagree.
The connection worked but the answer did not come back in a usable state. Reload the tab once. If it happens twice in a row, email and say roughly when it started.
Click the Link Adder button in the toolbar, pick a list, and it is saved. You can also right-click anywhere on a page and choose Add to Link Adder without opening the popup at all.
Link Adder replaces the new tab with your own lists: the lists along the top, one tile per link, and a search box. Chrome asks you to confirm this change before it takes effect, and will not apply it quietly.
Chrome does not let an extension hand the new tab back while it is still installed, so the only way is to remove it: go to chrome://extensions, find Link Adder, and click Remove. Nothing is lost by doing this. Your lists live on the server, not in the extension, and stay reachable at www.linkadder.com.
Deleting moves a link to the Recycle Bin, which sits at the end of your lists. Open it and drag the link back to where it belongs. Nothing is gone for good until you empty the bin, and emptying it makes you type EMPTY RECYCLE BIN in full first, precisely so it cannot happen by accident.
The new tab page draws from a copy held on your own machine, which is what makes it open instantly instead of waiting on the network. That copy refreshes on its own shortly after. If you want it immediately, reload the tab.
Link Adder stores three things, and nothing beyond them:
All of it sits on linkadder.com's own server. None of it is sold, and none of it is shared with anyone. Nothing is recorded unless you explicitly save it, so what is held is a list you built rather than a record of where you have been. The privacy policy covers this in full.
Email ltdninja@iadb.com from the address on the account and say you want it removed. The account and every link in it are deleted outright, not just hidden.
If Link Adder does not do a thing you need, that is worth saying. Feature requests go to the requests page when you are signed in, or to the same email address as everything else.