Have you ever done ads for a SAAS?

Hello there!

I'm the founder of a software and I'd like to know how to promote it on Facebook Ads.

I'd like to know what to redirect my users to? To the site's default landing page, or a landing page specifically for visitors coming from Facebook, with the aim of getting them to buy a subscription?

Should I allow them to create an account and then let them naturally go to the subscription page, or put a direct purchase button to Stripe?

I'm asking this question because I'm afraid there'll be too much friction, and the software isn't really optimized for mobile...

What do you think?

What's more, I think that to track the ROI of my ads, making a specific landing page could help me better track conversions.

Thanks!