Why can't I install a basic rails app for my online store?

[bonhoeffer]

I want to fully control my rails site, but have a shop with a shopping cart. I am planning to use: https://github.com/Shopify/shopify_app

I couldn't get my existing site to work after following all the instructions, I kept getting:
'''
Started POST "/login" for ::1 at 2023-12-14 07:22:17 -0600
Processing by ShopifyApp::SessionsController#create as HTML
Parameters: {"authenticity_token"=>"[FILTERED]", "shop"=>"timberlore.myshopify.com"}
[ ShopifyApp | INFO | Shop Not Found ] Installed store - timberlore.myshopify.com deduced from user session
[ ShopifyApp | INFO | Shop Not Found ] Installed store - timberlore.myshopify.com deduced from user session
Rendering /home/tim/.rbenv/versions/3.1.2/lib/ruby/gems/3.1.0/gems/shopify_app-21.8.1/app/views/shopify_app/shared/redirect.html.erb
Rendered /home/tim/.rbenv/versions/3.1.2/lib/ruby/gems/3.1.0/gems/shopify_app-21.8.1/app/views/shopify_app/shared/redirect.html.erb (Duration: 575.0ms | Allocations: 107159)
Completed 200 OK in 653ms (Views: 576.3ms | ActiveRecord: 0.0ms | Allocations: 175405)
'''
so i created a new rails app from scratch and followed the directions exactly. however, I still have this error:

I can't find how to give permissions in the partners app. Getting this to work is only the first step in getting my real application to work. 

I greatly appreciate any help getting past this and appreciate any specific links that help me solve my problem.