REST API JMeter Script

I want to work with a Jmeter expert freelancer remotely for few hours this weekend. Im beginer to intermediate level with jmeter. I need a reusable JMX file that will let me stress-test our REST API. The flow is straightforward: first, the script must obtain an OAuth 2.0 access token and keep it available for every subsequent sampler; next, it should hit the file-upload endpoint and push a sample CSV using multipart/form-data.

Please capture all correlation values (token, upload IDs, etc.) with regular expressions or JSON extractors so the run can scale with multiple virtual users. The test plan has to be cleanly organised with clear naming, user-defined variables for host, credentials, and file path, and a separate thread group ready for ramp-up tuning.

Deliverables
• A JMX file that signs in via OAuth 2.0 then uploads the CSV as multipart/form-data
• A short README explaining which variables to edit and how to run the test in JMeter 5.x+

I will validate the script by running it with 10, 100, and 500 virtual users and checking that every sampler returns HTTP 2xx without unhandled errors.