You can use a nip05 address, like https://nostree.me/, but I can see that you are using a gmail address as a nip05 address, so that wouldn't work. You can try to get a nip05 address or you can help the development of the project and get one through the nostree geyser page https://geyser.fund/project/nostree/rewards which would give you a valid nip05 address and also a vanity nostree url like https://nostree.me/.