Hi @Belzakura! Welcome to using ODK!
So one super confusing thing about ODK that I think is causing your troubles is that you are using app-designer, which is part of ODK2, but trying to apply directions from ODK1. There are two tool suites, ODK1 and ODK2, and they aren’t cross-compatible.
Here’s some info on choosing the right tool suite for you:
https://docs.opendatakit.org/odk2/select-tool-suite/
If ODK2 and app designer are what you want, then for the constraint, you’ll want to follow info here in ODK2 docs: ODK-X XLSX Converter Reference — ODK-X Docs
For example, in one of our surveys in 2018 we were collecting year of birth in variable q305_2. So we had a constraint:
(data(‘q305_2’) >= 1919 && data(‘q305_2’) <= 2018) || data(‘q305_2’) == 9998
and our message was:
Year {1919-2018, 9998 if don’t know}
Hope that helps!
Best,
Caroline