Besides companies that have MAC agreements, can any Microsoft partner or customer procure via the Azure Marketplace?
Yes, any Microsoft Partner can procure and does not need a MACC, or an EA signed with Microsoft.
Azure Marketplace helps you simplify the procurement process through different purchasing options. If you purchase products using a credit card associated with your Azure account, all purchases will be consolidated on a single invoice and billed to the credit card of choice. If you are a large customer, you can purchase using an Enterprise Agreement. With an EA, any software purchases are automatically included in your Azure invoice. Your invoice will contain Azure usage charges first, followed by Azure Marketplace charges.
When you purchase through Azure Marketplace, you eliminate the complexity of managing individual vendor relationships and invoices. You get a single, consolidated monthly bill from Microsoft that includes both your Azure Marketplace purchases and your Azure charges.