Looks like the DeepLink request handler is not started.
Did you correctly add the 'StartDeeplink' startup microflow of the DeepLink module in your AfterStartup?
Check your log message during startup.
I'm having the following problem with the forgot password link:
Couldn't find this localhost's page No web page was found for this address. Web:http://localhost:8080/link/invite?GUID=5cdb79a8-0159-4b64-b42b-86cb1edf885b
HTTP ERROR 404
I've seen some similar things here on the forum, but it still doesn't work.