You have been invited
Somebody at your agency has invited you to Devign Agency Suite. The invitation is inside the link you just followed, so keep that link: the app reads it from there, and there is nothing on this page to write down.
Get the app
Then open your invitation link again
Tap the link where you received it. Typing the address in by hand is not the same thing: a phone hands a link to an app only when it is tapped, so a typed one arrives back on this page.
Still nothing? The app may be signed in as somebody else. Sign out first, then tap the link again.
Keep the whole link
Everything after the # in the address is the invitation itself. It is not a reference to one: it is the thing that lets you in, which is why it never reaches us and why nothing on this page can show it to you.
So forward the link whole. A link that was shortened, wrapped by a chat app, or copied in two pieces has lost the part that matters, and the app will say it is incomplete.
Because it lives after the #, your invitation is stripped off before the address is ever sent. It is in no log of ours and is passed to nobody in between. Treat it like a password all the same: it is one, once.
If it has stopped working
An invitation is good for 14 days, and it works once. If yours has run out, or it was already used, ask whoever invited you for another. It takes them a few seconds from the roster.
A new invitation replaces the old one, so once they send it, only the newest link works.