I'm in the US, also says page not found for me.

Very strange. It doesn't work. I shared directly from the f-droid client droid-ify

https://f-droid.org/en/packages/de.westnordost.streetcomplete/index.html

Same in EU

Oh weird. That's shared from droid-ify which is an f-droid client.

Here's the proper link https://f-droid.org/en/packages/de.westnordost.streetcomplete/index.html