Good day! Just want to apologize for my English (this is not my native language).
We are developing a small application using the Coinbase API. The bottom line is that our wallet will receive money (that is, we need a request for coins) and from the same wallet money will be sent to other users. The problem is that when creating a replenishment request, the server gives an error "type not specified". However, the type is indicated there (request), and if the type is changed from 'request to' send 'then everything works.
Most probably you guys are trying to integrate automatic withdrawal system through Coinbase API. As far as i know that Coinbase current API have got the features of generating different deposit address. Through this process users gonna get new deposit address for every single click and deposited fund will be stored on your common wallet address.
For withdrawal you can go for manual or automatic. If you wanna make all withdrawals manually then you have to collect details by your own from your admin backend. After collecting withdrawal and amount details you can release fund from your main wallet one by one. Some API users like his way to get rid off unexpected wallet hack. If you wanna keep it automatic then you will have to integrate it through someone who is well experienced with it. In automatic withdrawal you will be notified by API providers for every single transaction and after confirmation from your side fund will be sent to user requested address.