Content for Newsletter Page

I am having issues creating a channel/collection for my newsletter page please help me

my routes.yaml looks like
routes:
/:
data:
post: page.home
template: page

/newsletter/:
controller: channel
data: page.newsletter
filter: tag:Newsletter

collections:
/articles/:
template: index
permalink: /{slug}/

taxonomies:
tag: /{slug}/

here is my newsletter page ​​https://www.conornee.com/newsletter/ and my newsletter posts which yes are tagged with Newsletter are not populating also is there any way to add css to the post view that populates like on here www.aliabdaal.com/friendzone?

P.S if there is any other way to have all posts tagged with newsletter appear under the page I am all for it.