URL for artifacts with / in the branch name

our naming convention on windows projects is features/new-thing, since the windows guys like sourcetree and such tools.
my problem is that i cannot download the artifacts via URL, but if I open a branch without / in the name it works.
I’ve tried the URL with %2F instead, or even -, but had no luck.
I appreciate any help. thank

edit: nvm, ive just now noticed that it probably wasnt the /, but the repo was private.
is there a way, without using the API to download the artifact from a private repo?