You aren't required to post on other social media sites to get an upvote from the dMania bot. Your post does need to be popular though. Otherwise people could just put up the max # of posts per day and have a higher chance of being picked.

This is copied directly from the dMania FAQ section, and hopefully it helps you to understand the requirements and have a better chance of being picked for an upvote from the dMania Bot.

How do I get upvotes from the dMania bot?

The dMania bot selects a random post on the Trending page every time he reaches 100% voting power. At the moment the bot selects a post every hour. The bot will select only posts with above average upvotes and rewards. To get an upvote from the bot, create great posts and collect rewards and upvotes from the community. Only users who are active on dMania and don't spam will receive upvotes from the bot.

Requirements to get an upvote :

• Don't spam. Maximum 20 posts in the last three days.
• Upvote other posts. Minimum 5 upvotes on other posts in the last three days.
• Collect above average rewards and upvotes. Posts with $0.01 rewards and one upvote won't receive an upvote from the bot.
• Every user receives maximum one upvote per day.
• Posts have to be in english.