Here's a snapshot of the results for this landing page from May – Aug 2019 – and continues to this day
I think landing page design is important. But the design, button color, etc IS NOT the reason people opt-in.
What makes people convert is the promise
It's the congruency from the first call to action they saw (where they're coming from to your landing page).
Here's the landing page that converts:
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Let me point out a couple of things about why this is the best lead generation landing page for me yet.
1. I'm giving away a spreadsheet. Big deal. But the promise of calculating profit first deposits (that's the product btw) automatically is what people WANT. They don't want a spreadsheet.
2. A secondary promise; “your profit first accounting will be easier using this spreadsheet”. This works because MOST people HATE accounting…but it's necessary. And this is painting a picture of a better future.
3. I share my story – a SHORT story that empathizes with my prospect. I know what they're going through…so they realize that I know how they feel. And WHY I created this FREE spreadsheet. I'm giving them a solution that works for me.
4. The button text. It's in first person. “Give ME the Spreadsheet”. Not download now, click here, or Get the spreadsheet. 
I'm not saying those other phrases don't work.
But after all this time, this landing page consistently gets +60% opt-in.
This brings me to my next BIG point.
The SINGLE reason this landing page works is that people coming to it are ALREADY “sold” on getting the freebie.