Actually, I don’t think it can (saying that as the one who wrote it). It look like @Admin_CMV wants a running total in a separate column, whereas my solution in the linked post addresses a totally different issue.
Making a running total in Airtable—whether it’s for downloads, a checkbook register, or anything else—can be done, but it’s tricky to set up. Airtable records (rows) have no knowledge of each other because, from a database perspective, record order is irrelevant. Records are all about maintaining a consistent internal data structure across all records, regardless of order. However, people coming from a spreadsheet paradigm see Airtable’s default grid view and often assume that most (if not all) of the things they could do simply in a spreadsheet—including running totals, arbitrary cell referencing, etc.—can also be done in Airtable. The reality is that not all spreadsheet concepts cross over to a database with ease, if at all.
Anyway, I did say that it’s possible in Airtable with some tricky setup. Here’s a post that describes the setup involved: