You need to create a menu item pointing to the extension's view. Go to Menus > Main Menu > New, choose the extension's menu item type, and select the appropriate view.

This is usually a PHP version issue. Check that your server is running PHP 8.1 or higher. You can verify this in System > System Information.

Our extensions use your template's CSS variables where possible. If things look off, check that your template supports CSS custom properties and isn't overriding the component styles with conflicting rules.

Uninstall the extension via System > Manage > Extensions, then reinstall it. This will recreate all database tables with default values. Warning: this deletes all existing data.