Here are some steps you can take to increase your chances of winning the buy box:

Competitive Pricing: Ensure that your product is competitively priced. If your price is too high compared to other sellers offering the same product, you're less likely to win the buy box.

Fulfillment Method: If you're using Fulfillment by Amazon (FBA), you may have a better chance of winning the buy box since Amazon favors FBA sellers due to their reliable and fast shipping.

Product Availability: Make sure your product is in stock. Products that are frequently out of stock are less likely to win the buy box.

Product Condition: If you're selling used or refurbished items, ensure that their condition is accurately described. Customers are more likely to buy products that are accurately represented.

Performance Metrics: Maintain a high seller rating and excellent customer service. Positive feedback, fast shipping, and quick response times to customer inquiries can improve your chances of winning the buy box.

Product Listing Optimization: Optimize your product listings with high-quality images, detailed descriptions, and relevant keywords. This can improve your product's visibility and attractiveness to buyers.

Winning the Buy Box: Sometimes winning the buy box is not immediate, especially for new sellers. Keep monitoring your performance metrics and make adjustments to your pricing and other factors as needed.

If you've taken these steps and still don't see the buy box option, it's possible that there may be other factors at play. You may want to reach out to the platform's seller support for further assistance and guidance tailored to your specific situation.