How to display a views block on pages with a specific combination of URL patterns?
Using the Block Visibility Groups module, perform these steps:


Define a new Block Visibility Group, say you name it "Group pages".
For this newly created *Block Visibility Group" (named Group pages"), add 2 conditions by selecting a condition related to the "Request path", which look like so:


Return true on the following pages: group/*.
Do not return true on the following pages: group/*/node/create/article (not sure if you want the /article suffix to be added, pick what fits your content types).

If you also want to show the Global Blocks, then mark the Show Global Blocks as checked.
Use the Place block button to place the Views block in the theme region of your choice.


Notes:


if you're not familiar yet with this module, then have a look at the video about Block Visibility Groups - Drupal 8 Blocks but Better.
if this question was about D7, I'd use the Rules block visibility module and specify similar Rules Conditions (based on the same current paths).
don't get confused with all the Group-stuff (the Group module, versus the Block Visibility Groups module ...)