There are two general ways of connecting to BI Book API. Either by using REST API or Odata connection. The latter is the recommended connection type. For instructions on how to do this see the API docs for BI Book and API docs for BI Book forms from these links:

BI Book:

BI Book forms:

For Odata connection to excel follow these steps:

1. Select Get Data > From Other Sources > From OData Feed 

2. Enter the url in this format:

    Here 52 is company id in BI Book:

3. Select basic auth and enter the following details:

4. Odata connection completed