The hand is placed on the tapered pin of the tray. You can glue them* if you prefer, but this is not necessary.
The bowl is ...placed on the recess in the hand. Also with this one: If you prefer, you can glue them, but this is not necessary. (Although I recommend a bit of double sided tape or gluing* for a solid placement.)
Print all parts as positioned in the STL files. Use your own favorite settings for a sleek looking result. With my print I used a 0.4 nozzle, layer height 0.2 and infill 15%. None of the parts require a support. For the bowl you can use a small brim (I used none).
The different parts can easily be printed in a different colour.
* The hand can also be rotated 180° for a different orientation. However, then the Bowl cannot be used. (see foto) If you want to be able to change later, don't glue!