They're Signing Up! How do we convert?

We've got 100+ subscribers to our newsletter where we share inventory updates and other information that we think would benefit those who join read us. It's so great to see so many folks join us and want to know more about us.
There's just one tiny problem.
We can't get them to convert to an actual paid user. We tried a promotion on what was supposed to be our first day, 4/3/2024, where we sent out a broadcast letting these folks know they could join today for 25% off their first month. There were no takers. Which I can understand we didn't do a good job of prepping the announcement, we woke up and just decided to do it. However I had hoped there would be at least a few takers.
For those who have had similar problems, how did you get your readers to convert to customers?
To preface, we are going to be asking those who are using our service to provide reviews as we know that's important. We're also making updates to our site to show which sets are currently being rented.