I'm not familiar enough with Postman to really help you with that specifically, but if you only have 150 clients in your network then it's probably easier for you to set the 'perPage' value in your request to the max (1000) and not worry about dealing with multiple pages of clients.
Check the documentation for this API call as it defines the requests parameters (including perPage). Set that parameter in your Postman request and you should be good to go.
https://developer.cisco.com/meraki/api-v1/#!get-network-clients