help with traffic for local businesses

Hi, I think it's been about 3 months since I started digital marketing.

First I started using Pinterest to try to earn money to invest in paid ads on Google ads and Facebook ads, but so far I haven't been able to sell any products as an affiliate.

So I thought about using Pinterest to do*print on demand but I didn't have the money to buy a domain and without a domain I couldn't set up the checkout on Shopify, although I still have the account even with the help of support I couldn't solve the problem.

So I had the idea of ​​creating traffic for local businesses, and continuing with organic traffic on Pinterest. In addition to making money, it's a good opportunity to learn and get used to Facebook's ad manager.

I did some more research, I still had some questions, especially if I send traffic to a store or company, do I still need to buy a domain?

How would I segment the audience for these businesses?
I got a contract from someone to use with companies but I don't know if it's safe to use so I don't get hurt

Can you recommend videos or books too?