Joining a Zoom meeting as a participant
Before joining a meeting, you must make sure that you have the Zoom app installed on your device and that you are already logged in to your Zoom account with your @student.diak.fi username and password.
Remember to give preference to the desktop app whenever possible, as the browser-based and the mobile app have limited features (e.g. whiteboard editing and breakout room self-select might not be available, limited number of cameras per screen, etc).
If you receive a Zoom meeting invite link, click on it to join the meeting. The link will open in your device's default internet browser, and it will attempt to automatically open the Zoom app. If you are on a desktop computer, you might get a browser pop-up asking for permission to open the Zoom app. Tick the option to always allow the app to open the link so you won't have to click this separately in the future, and press "Open Zoom Meetings".

If you don't get any such pop-up and Zoom doesn't start, it probably means Zoom is not installed on your device.
You might also be asked to provide a passcode, which the host should have sent along with the invite link.
If asked, select the default option "Join with Computer Audio". Depending on the meeting's setup determined by the host, there may be additional steps like testing your camera and microphone settings before joining.

Joining an online lecture on Diakle
Log in to Diakle, find the respective course from "My Courses", and then go to the section where the Zoom activity is.

Click the meeting title to open the activity, and then press "Join Meeting".

When joining through the Join Meeting button on Diakle, you do not need to provide a passcode or login to Zoom separately, assuming you're already signed in to the Zoom app on your device. Zoom meetings on Diakle use the same Office 365 Single Sign-On credentials that are used to login to Diakle. The meeting should open on the Zoom app automatically, but if you are redirected to a browser tab asking for permission to launch the Zoom app, allow it in order to proceed.
If you run into browser error messages when trying to join a meeting from Diakle, it may be because you have signed in with two or more Office 365 accounts on the same browser at some point, and the browser is having a hard time differentiating between credentials.
You can get past this either temporarily by opening a private window on your browser, logging in to Diakle and so on, or more permanently by clearing your browser cache, and only using one Office 365 account per browser henceforth.
Depending on the meeting's settings, you might be asked to wait until the host starts the meeting, or lets you in.
If you join using your mobile, remember to press "Wifi or Cellular Data" in order to connect to the meeting's audio.

If you are using an iPad, press the option to join audio with Wifi.
