Access to the admin is obtained through links containing a one-time passcode (OTP). These links are generated from within the server and expire within a couple hours of being issued.
Once opening the link, continued admin access is granted to that particular browser. Subsequently, the admin can be accessed by going to the server droplet's IP address, e.g.: https://188.8.131.52
If the browser cache is cleared, then the user will see 'Authentication failed' and need a new admin link.
To create a new link, within the server run
lamassu-register followed by a name to identify the recipient or purpose. For example:
If sending the link to another device, send it over a service which doesn't auto-preview the link (and thus invalidate it). Signal and Keybase are good for this, or within codeblock formatting in Wire, Riot, or WhatsApp.