There are usually multiple strategies to successfully completing a scenario; these can be discussed in the comments below, written down in an additional section of the article or added to an existing subsection.
In this park, you should focus on cramming as much rides and shops as you can on the skyscraper, since that area isn't filled with scenery like the ground level. You have the best selection of roller coasters you could wish for that intent. Cram together as many roller coasters as you can, preferably cheap ones like the Virginia Reel or the Wooden Crazy Rodent Roller Coaster, then fill the rest of the space with some less intense rides and some shops. Just filling up the skyscraper alone will give you around 800-900 guests. A Vertical Roller Coaster lends itself to building a lift for your guests, so they don't have to walk all the way up and arrive there exhausted. This can also be a huge money maker, even though it won't come cheap constructing it. Once all the possible space on top of the tower is gone, you can either build in the tower itself or build on the ground. However, both methods will drain your cash, so you'll have to let your rides and shops bring in some extra cash. When you do get enough cash, keep building lots of rides and shops and you'll reach your goal in no time.