First, allow notifications so the site can alert you even when it's closed.
Now connect your account so the server can watch your inventory for new Huge/Exclusive pets.
You'll sign in on the official BIG Games site. This app never sees your password.
Status
Watching in the background
Checks every
~5 minutes
You can close this tab — the server keeps checking and will push a notification to this device when a new pet shows up.