The api is required to interrogate the Discogs database and return required information. Ideally a barcode scanner will be used to scan the vinyl or CD but for older releases with no barcode, a facility to type in a catalogue number (for example) will be needed.
The api will then send that information to Discogs and effectively ask "what is this?". Discogs will return with the release details (or possibly a selection to choose from) as a list of data which will then populate the spreadsheet
This must be a web based application which will be hosted on the company's domain.