The integrations that are visible on the App Center page are based on the type of business that was selected when you were first setting up your account.
For instance, if you selected "Musical Instrument Repair" as your shop-type, you will not see the Kabuto app card, as this integration pulls in alerts that are generated when computers are having issues. If you selected "Computer Repair", you will see the Kabuto card.
If you would like to change your business type so that you can see cards that are not currently visible to you, just head to Admin > Initial Settings Wizard and navigate through to the Business Settings step. On this page you can change your Primary or Secondary category, and also select additional categories if you wish.
If you have any questions about specific integrations, feel free to reach out to email@example.com.