Read the subreddit rules first
Every subreddit is run by its own moderators with its own rules, and a post that breaks them is removed regardless of how good it is. Before you post, open the community's About tab and read the rules: what topics are allowed, whether you need a flair, whether titles need a tag like [Question], and how the community treats links.
Then read a few of the top posts of the week. They show what that community upvotes, the length people expect, and the tone. The drafts here are a starting point; adjust them to what you see.
Posting the same thing in many subreddits at once is treated as spam on Reddit. Pick the community where your post fits best.
Why Reddit posts must not read like ads
Reddit users vote on every post, and they vote down anything that looks like marketing. Moderators remove it, and accounts that do it repeatedly get banned from communities or from Reddit.
The posts that work for a business are the ones that would be worth reading even if your company did not exist: a lesson learned, an honest breakdown, an answer to a common question. That is why the generator does not offer "promote something" for Reddit, and why it writes drafts as posts, never as ads.
If you mention what you make, say so plainly and only where the community allows it.