You can create your first application upon adding the bot with /config. Once an application is created, /configbecomes a configuration menu to configure applications, set up permissions, channels, or settings.
First, list out who have applied with /apps. Then, choose who you'd like to review and type /review <member>. <member> can be a member mention, full name without a discriminator, nickname, or user ID.
Make sure that you have link previews on in settings. User Settings > Text and Images > Make sure Link Previews is on. Make sure that Show emoji reactions on messages is also on so that you can see the buttons.
This means that you've found a bug within the bot. The best thing you can do is join the support server and give some context about what you were doing or what happened that you think that would've caused the bug.