question

And how can i get merchantid using PhoneGap to follow OAuth flow and retrieve merchant access token???? Once i get merchantid I will be able to retrieve token via OAuth and later use the clover api with it, but i do not find a way to get the merchant_id once the app was downloaded by the merchant. It will be grateful if you can give me a solution to my problem. Thanks again.

Merchant ID is an optional url parameter that you can pass in order to "auto-select" the merchant if the person has multiple merchant accounts linked. For use cases like above, we are presuming that the web app has it's own account management outside of Clover's ecosystem (i.e. any product that exists across multiple platforms) to which the Clover Merchant ID would be linked to.

For your use case, all you need as a base is: https://www.clover.com/oauth/authorize?client_id={clientId}