If clicking the "Generate New Invite" link in your welcome email doesn't work please try the following 5 steps.
1) Login to your Discord app or on the web here: https://discordapp.com/login
2) Follow your "Generate New Invite" link in your welcome email and copy the invite link on your Discord invite page. The link is located at the top of webpage and looks like this: https://discord.com/invite/ABCDEFG
3) Go to your Discord app and click the (+) in the lower left and join sever.
4) Paste your invite link from the top of the invite page to join the server. An example is below.
5) Activate your account.
On arrival to the Discord server the LaunchPass Bot will message you, simply reply with your activation code found in your email. Your activate code will look like this: !ABCEF
After all this is done and you want to access the account on other devices, you just download the app and login using the same email and password. No need to click on 'Generate a New Invite'.