OAuth error

[nkstnkst]

I followed the instructions. When I try to install the app by visiting /api/zoomapp/install, this error happens.

backend_1   | INSTALL HANDLER ========================================================== 
backend_1   | 
backend_1   | 1. Begin add app - generated state for zoom auth and saved: 75ZsRuO7L6t3gM5Uf3vx4QjwGDcCwIhUJeZ9A4DvCEw=.ba72b981a52beb7b37dd48fba2798c956f90a99c43e62465794e29d0418cecf28970acfe56e6f960805acaac6a258c3d3d172c0230a578ed81094af30005ecff 
backend_1   | 
backend_1   | 2. Redirect url to authenticate to Zoom: "https://zoom.us"/oauth/authorize?redirect_uri=https%3A%2F%2F6d09-76-132-152-88.ngrok-free.app%2Fapi%2Fzoomapp%2Fauth&response_type=code&client_id=%22YXf4n__BTL68qDVZTf1gQ%22&state=75ZsRuO7L6t3gM5Uf3vx4QjwGDcCwIhUJeZ9A4DvCEw%3D.ba72b981a52beb7b37dd48fba2798c956f90a99c43e62465794e29d0418cecf28970acfe56e6f960805acaac6a258c3d3d172c0230a578ed81094af30005ecff 
backend_1   | 
backend_1   | 3. Redirecting to redirect url 
backend_1   | 
backend_1   | GET /api/zoomapp/install 302 1.033 ms - 788
backend_1   | GET /api/zoomapp/%22https://zoom.us%22/oauth/authorize?redirect_uri=https%3A%2F%2F6d09-76-132-152-88.ngrok-free.app%2Fapi%2Fzoomapp%2Fauth&response_type=code&client_id=%22YXf4n__BTL68qDVZTf1gQ%22&state=75ZsRuO7L6t3gM5Uf3vx4QjwGDcCwIhUJeZ9A4DvCEw%3D.ba72b981a52beb7b37dd48fba2798c956f90a99c43e62465794e29d0418cecf28970acfe56e6f960805acaac6a258c3d3d172c0230a578ed81094af30005ecff 404 0.714 ms - 1052
backend_1   | Error: Not found
backend_1   |     at /home/node/app/server.js:50:17
backend_1   |     at Layer.handle [as handle_request] (/home/node/app/node_modules/express/lib/router/layer.js:95:5)
backend_1   |     at trim_prefix (/home/node/app/node_modules/express/lib/router/index.js:328:13)
backend_1   |     at /home/node/app/node_modules/express/lib/router/index.js:286:9
backend_1   |     at Function.process_params (/home/node/app/node_modules/express/lib/router/index.js:346:12)
backend_1   |     at next (/home/node/app/node_modules/express/lib/router/index.js:280:10)
backend_1   |     at /home/node/app/node_modules/express/lib/router/index.js:646:15
backend_1   |     at next (/home/node/app/node_modules/express/lib/router/index.js:265:14)
backend_1   |     at Function.handle (/home/node/app/node_modules/express/lib/router/index.js:175:3)
backend_1   |     at router (/home/node/app/node_modules/express/lib/router/index.js:47:12)