Help setup of Reverse Proxy with ARR and UrlRewrite on IIS

Question

Hi, I could not find all the tags I was hoping for on this and only found IIS to match.
I am trying to setup a reverse proxy with Application Request Routing 3.0 and IIS UrlRewrite 2.0. Trying to get a site https://beta-services.companyname.com/avatars to reverse proxy to https://beta-services2.companyname.com/avatars. https://beta-services is external (dmz) and https://beta-services2 is internal.
Requests to https://beta-services.companyname.com/avatars/filename.jpg should pull and return the avatar from https://beta-services2.companyname.com/avatars/filename.jpg
there are other apis under https://beta-services.companyname.com/api1name, https://beta-services.companyname/api2name but I dont want those to change.
I have installed ARR and URLrewrite on a windows 2019 server using IIS. We have ARR enabled for reverse proxy.
Here are my inbound and outbound rule first in the web.config for https://beta-services.companyname.com

here are the images of inbound rules and outbound rules
In bound

InBound Rules

and finally the outbound rules

This does not seem to be doing what I want and it seems to cause all the other APIs under https://beta-services.companyname.com to throw 500 errors
Trying https://beta-services.companyname.com/avatars/1EADB8A1-B840-494B-BAF6-D70A85EDC8EB_1.jpeg results in 404 not found even though the image would render with https://beta-services2.companyname.com/avatars/1EADB8A1-B840-494B-BAF6-D70A85EDC8EB_1.jpeg.
what am I doing wrong?