Adding Login to Shiny App

Question

EDIT: I heavily edited this question, because it was not very good.

I'm trying to add a login to a shiny app, so that only users with the correct username (test) and password (test) can view the app. I'm a frequent R user, but have very limited experience with Shiny (and HTML) and I need to edit someone else's shiny app to add this login feature.

I was trying to use this example Starting Shiny app after password input

The app I'm trying to add the login to uses dashboardPage and is fairly complicated, but I just want to know how to get this working with a bare minimum example such as this basic dashboardPage template. https://www.rdocumentation.org/packages/shinydashboard/versions/0.6.1/topics/dashboardPage

I tried to edit the code from the other stack overflow answer in the following way but it did not work.

 rm(list = ls())
 library(shiny)

 reports = data.frame(list.files("",full.names=FALSE))
 colnames(reports) = c("Reports")

 Logged = FALSE;
 my_username <- "test"
 my_password <- "test"

 ui1 <- function(){
   tagList(
     div(id = "login",
    wellPanel(textInput("userName", "Username"),
              passwordInput("passwd", "Password"),
              br(),actionButton("Login", "Log in"))),
tags$style(type="text/css", "#login {font-size:10px;   text-align: left;position:absolute;top: 40%;left:
           50%;margin-top: -100px;margin-left: -150px;}")
  )}

 ui2 <- function(){ source("ui.R", local = T) } 

 ui = (htmlOutput("page"))



 ##############---------------------------------------------------------------------################

 ##############---------------------------------------------------------------------################
 ####Server function
 server = (function(input, output,session) {

   USER <- reactiveValues(Logged = Logged)

   observe({ 
     if (USER$Logged == FALSE) {
     if (!is.null(input$Login)) {
     if (input$Login > 0) {
      Username <- isolate(input$userName)
      Password <- isolate(input$passwd)
      Id.username <- which(my_username == Username)
      Id.password <- which(my_password == Password)
      if (length(Id.username) > 0 & length(Id.password) > 0) {
        if (Id.username == Id.password) {
          USER$Logged <- TRUE
        } 
      }
    } 
  }
}    
   })
   observe({
    if (USER$Logged == FALSE) {

  output$page <- renderUI({
    div(class="outer",do.call(bootstrapPage,c("",ui1())))
  })
}
if (USER$Logged == TRUE) 
{
  output$page <- renderUI({
    div(class="outer",do.call(navbarPage,c(inverse=TRUE,title = "Contratulations you got in!",ui2())    )    )
  })
  print(ui)
}
   })
 })

runApp(list(ui = ui, server = server))

Where ui.R is local and is simply

 library(shiny)

 ui = dashboardPage(
   dashboardHeader(),
   dashboardSidebar(),
    dashboardBody(),
   title = "Dashboard example"
 )

But I get the error

Warning in file(filename, "r", encoding = encoding) :
  cannot open file 'ui.R': No such file or directory

I'm just trying to figure out how to edit the server/ui parts of the template for the login so that I can apply this to an app that uses dashboardPage. I was able to get it to work with a simply histogram shiny app, but not with anything else.