Dropdowns, databases and boolean values

Good day everybody. Total Corvid Newby here.

I need to present a drop-down list from which a choice will populate the second drop-down list,which will change the repeater below accordingly. I really feel that I understand all the different elements and how they function, but I cannot get everything to work together. I have now watched 2 tutorial videos and according to me, followed the instructions step-by-step; no luck, both times. Is there perhaps something really obvious that I am missing?

Help, pretty please.

You can do something simple like this tutorial example here from Wix.

https://support.wix.com/en/article/corvid-tutorial-adding-collection-data-search-functionality#search-using-a-dropdown-element

Then get the value if the second dropdown list and filter the repeater with setFilter.
https://www.wix.com/corvid/reference/wix-dataset.Dataset.html#setFilter
https://www.wix.com/corvid/forum/community-discussion/filtering-repeater-with-a-dropdown

Or simply follow this tutorial video here.
https://www.youtube.com/watch?v=r0DLqkRDJ34