To join meeting you don't need an account. To start meetings, you need one.
There are free accounts and paid for accounts.
With 3 or more participants, free accounts are limited to 40 minutes meetings. You can start a new meeting after 40 minutes.
No built in real time automatic captions. But you can connect the audio output of the Zoom to an app like "Live Transcribe" for personal real time automatic captions, or even put the smartphone with the captions against one of the meeting participants camera to have all the participants see the automatic captions.
Remote human real time captions are possible.
It is possible to record the audio of the Zoom meeting.
It is possible to have automatic captions of the recorded Audio after the meeting.