The AI is held in a sub-folder of the main interface folder of the CumulusMX Installation.
Accessing it depends on whether you use the computer that hsost CumulusMX or from a nother computer on your local network. It cannot be accessed from a computer outside your local network unless you use some third party sofware such as VNC or rPi Connect.
If you use localhost:8998/ to access the default interface
then you should be able to use localhost:8998/ai2/
You might need to use: localhost:8998/ai2/index.html
If you use <ip_address>:8998/ to access the default interface
then you should be able to use <ip_address>:8998/ai2/ or <ip_address>:8998/ai2/index.html
Note: If you have used an alternative port number then this will obviously need to be used instead of the default port 8998 above.