There are two ways of inviting users.
Individually: You can send an email to the user you want to invite with a link for them to join your lab, after creating an account on Clustermarket.
If you would like to resend the invitation to a user who hasn't accepted the invite yet and extend the duration of the link go to Users > Overview > Edit (pencil icon) > Extend > Click "Yes, I'm sure".
โBulk: You can create a link with to send or publish to your lab members. When they click on it, it will prompt them to create an account on Clustermarket and they will join your lab under the specifications you've selected while creating the link.
Here is a short video showing how it works: