Most often it is waiting in the lobby. The host has to admit "MeetNotes Notetaker" from the waiting room. Also check the link is right and you have minutes left.
Ask the host to check the waiting room or lobby and admit MeetNotes Notetaker.
Check the meeting link you pasted is the full Zoom, Google Meet or Teams link.
Check you have minutes left. Automatic joining pauses at zero minutes.
Send it again: tap the microphone button, then Online meeting.
Good to know
The host can decline to admit it, like any guest.
The meeting shows the notetaker's status: joining, recording, or delivering the recording.
For an invite, notes@getmeetnotes.com joins only meetings you organise.