/!\ The game needs the expansion pack to work, don't forget to activate it:

In Project64, click on "Options" then on "Settings" in the "Options" tab, you must uncheck the "Hide advanced settings" box. Then you have to go back to the settings, there will be many more tabs, click on "ROM settings", and set the size of the RDRAM to 8mb.

More informations on:
https://romhacking.com/hack/return-to-yoshis-island-64-demo