You do not need a separate website for this business but having a professional website and email can help you gain credibility with suppliers.
If a supplier asks you for a website and you don't have one, you can just ignore that field and let your supplier know that you are selling on Amazon's marketplace and that you do not have your own website. You could also put your Amazon storefront link and see if they'll take that as well.
If you choose to create a professional website and email address, we suggest you include the following information on your website;
1. Your company name and contact info
2. That you work with and sell big name brands online
3. Optional: An e-commerce store where customers can purchase from you (some suppliers will only want to work with e-commerce sellers that sell on multiple platforms and not just Amazon).
A few easy to use website solutions are 1. Wix, 2. GoDaddy, and 3. Shopify.