Work Does not allow After-tax contributions to 403B

Hello, question is essentially the title, is it normal for job to not allow after tax contributions?

I called HR today and they said that i've contributed the 'max' to my 403b already which is 23,000 and then also the max to my 457 which is the same, but i can't do anything else including after tax contributions.

sidebar question: my employer match is 9,000 which seems on the lower side but i have no frame of reference to be honest.