You can join kintone from the invitation e-mail you received from another member.

1. Open the invitation e-mail that you received. The sender of the e-mail is "kintone <no-reply@cybozu.com>".
   
2. Check the inviter, and then click "Join kintone." For example, the following screenshot shows that Mary Smith is inviting a team member.
   
3. Type or copy & paste the login name and initial password shown in the e-mail, and then click Login.
   
4. When you are prompted to change the password, enter a new password and click Save.
   

You are now logged in to kintone.
When a "Welcome to kintone!" dialog is displayed, you can click Next and proceed to start to create an app.