A self-made list of companies, nobody needs accounts, you can't buy anything just click links to external websites... that's a directory. It's the Yellow Pages. And your business model of selling featured listings is the same as the Yellow Pages.
"A marketplace business is one that (1) connects demand (i.e. people who want a thing) with (2) supply (i.e. people who have that thing), and (3) leads to a financial transaction. These businesses do not generally own any supply, do not provide products or services directly, and (eventually) handle the money being exchanged. Simply put, their job is to provide a platform where the supply and demand efficiently find each other and transact successfully."
There's demand, supply and people eventually transact. The only missing part is handling the exchange of money.
Let's take a Sunday Farmers' Market, for example. It's a marketplace happening in the backyard of your school. That marketplace provides the platform for people to exchange goods and services and does not do anything related to money exchange. It just sells market spots to the farmers.
A directory has no chicken-and-egg problem. You have a list of businesses, who don't have to set up at your market at all since there isn't one. Any buyer that shows up at your directory can get value from it, since you're just pointing them to the business somewhere else.
You facilitate no transaction. You're not even transaction-focused, you're research-focused, with reviews and alternatives and all that. Vendors don't have to set up in your market, you can simply create their listing for them since it's just a directory. You're the Yellow Pages, not the Farmer's Market.
There's nothing wrong with that, but this series of articles doesn't apply to your site, as it's not a marketplace.