Debian linux - unstable apt download

trying to add repo but it appears to fail made harder by not being able to browse to source path

Debian unstable apt repo
Having some trouble getting this working missing file or something is not right
output from apt

Reading package lists… Done

E: Failed to fetch 404 Not Found [IP: 443]

E: Some index files failed to download. They have been ignored, or old ones used instead.

Is the repo set up alright i am unable to browse to the path it is returning above” brings up a 404 error ??

for now i am manually downloading and installing