Did you check this thread?
https://community.meraki.com/t5/Developers-APIs/Please-tell-me-how-to-solve-429-Too-many-requests/m-...
Purpose and importance
API call budgets define the number of API calls that an API client can make in a given amount of time and are a safeguard against runaway applications and malicious behavior. Call budgets (or rate limits) are a standard feature of high performance APIs across industries and working within the provided call budget is table stakes for any developer building an application that consumes the API. The best practice is for applications to manage API call budgets effectively and avoid making API calls in excess of the limit.
https://developer.cisco.com/meraki/api/#!rate-limit
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
Please, if this post was useful, leave your kudos and mark it as solved.