Lotech said, “I installed Cinnamon via AppCafe, but I don’t know how to switch desktop, I don’t see it in the login prompt”
On the login screen, below the fields for your name and password, you will see another field that probably contains the name of the last used desktop manager. Look for a small downward-pointing triangle. If you click on the triangle, the field box should open to list all other installed desktop managers. Select Cinnamon from the list and click the right-pointing white arrow in the blue box. If you do not understand what I mean, you can see this illustrated in the TrueOS Handbook @ Section 2.18
If you do not see Cinnamon in the list, then your installation was defective and you should install it again.