If you are just starting out and are unaware of how to dropship products or use depop, I'd recommend purchasing the guide.

If you want to learn from scratch as well as receive vendors which are an essential part of dropshipping, you should purchase the guide and vendor combined.

Vendors usually reply with 24-48 hours. But if they don't contact you back at all, it could be due to intense frequency of messages on their end. You may have to wait 24-48 hours and then contact again.