Copywriting, marketing & conversion questions

What are some good resources for improving these skills (specifically copywriting & marketing)?

I'm working on moiapi.dev and struggled to get users to sign up. I am wondering if I'm not explaining the benefit of the product clearly enough.

It has two equally important features to it (adding counters to your website & syncing your profile info across all accounts) and I'm not sure how to highlight both (or figure out which is the key one for users).