Use of Data API to store and get data from Collection

First of all let me tell you we are very new to MongoDB.

We are using Workday as our source of payroll data. Currently we were using Oracle database of store payroll data from Workday using Oracle Middleware. Then this data is exposed to third party to view employees earnings/deductions.

Now, as we are decommissioning Middleware and are in process of using MongoDB to store this data.
The data which will be stored in MongoDB should be exposed as an API endpoint.
Our API gateway system, Apigee will access this endpoint and get required data from the collection.

Our question is more from design perspective.

What we have thought is creating a ‘Data API’ in mongodb . In this, we create an API key and then use this API key to insert the data into the collection using insert API(insertMany). This insert will happen via an interface/program which will run in Workday and insert data from Workday to MongoDB using HTTP-POST.

Similarly, we will do a POST request of FindMany to get the required data from the collection once the insert is complete.

There are around 300,000 records in the document and the process will run monthly. Each month the previous document will be deleted and new one will be inserted.

We want to know if this design is the best way to store and get this data ?