Don't feel bad, that's actually a problem that a LOT of people have when they get started!
Here are some things you can try:
- Is the habitat complete? It needs to have a habitat gate and a path connecting to it. Otherwise the staff can't reach it.
- If you have a habitat gate, click on it. It will open a habitat window that will tell you if there are any issues with it. If it doesn't open the window, maybe the habitat barrier isn't complete?
- Try pausing and unpausing (if you build a habitat gate on pause, it won't register as a complete habitat until you unpause, and then pause again. Pause + unpause solves a lot of problems, it becomes a habit when you get used to it.
- Try all these things and then wait for a couple of minutes (unpaused), sometimes the staff need a moment to think and sort themselves out
If none of that works, try quitting and restarting
If THAT doesn't work, abandon the tutorial and open a sandbox zoo. I found the tutorial really frustrating and quit it early on. I find it much easier to learn in Sandbox mode, where you can figure out the basics for yourself.
Here's an alternative tutorial. Try figuring out how to do these things in Sandbox, in this order:
1. Place some staff buildings - 1 of each
2. Connect them with staff paths
3. Build a basic habitat, with barriers and a gate
4. Connect the paths to the habitat
5. Hire some staff - keepers, mechanics and caretakers
6. Buy some animals from the trade centre
7. Send your animals to the habitat
8. Find out what enrichment they need in their habitat and put it in
9. Find out what terrain they like and use the terrain tool to paint that in
10. Add some plants
11. Watch your staff feed and clean up after the animals. Double click on an animal! Watch an animal in camera mode
12. Build some normal paths for guests to walk on
13. Place down some buildings for guests - food, drink, benches, bins, put some donation boxes by the habitat
14. Hire a vet and a security guard
15. Open the construction tab and try building something, anything you like, maybe a small shelter for your animals inside their habitat
16. Go to the facilities tab and buy some exhibit boxes
17. Go to the exhibit trade centre and buy some exhibit animals you like
18. Put them in the exhibit boxes - 1 animal type per box
19. Click on the exhibit and click through the windows to see if there are any issues with temperature and humidity - fix those
20. Go to the staff menu and find vet research. Give your vet an animal to research by moving their name onto the animal
21. Go to the mechanic research tab and set your mechanic to research something. It will unlock more themed pieces for you
22. Decorate your zoo with some foliage
23. Go to the blueprints tab and find a blueprint you like, place it down
Now you know all the basics. Enjoy! You're getting it!!
You can now open a Franchise zoo and try doing this again while watching your finances

Don't worry if you fail to make a profit the first few times, it takes some practice!
Or if you prefer building, keep playing in sandbox
Don't be afraid to play on pause a lot of the time, things move fast in the zoo!