To obtain credential to access docs in google drive:

library(googlesheets)
shiny_token <- gs_auth()
saveRDS(shiny_token, "shiny_app_token.rds")
googlesheets::gs_ls()

then

googlesheets::gs_auth(token = "shiny_app_token.rds")
sheet_key <- ""
ss <- googlesheets::gs_key(sheet_key)

the key can be taken from the address of the sheet.

To try locally:

shiny::runApp()

To deploy:

library(rsconnect)
deployApp()

Some pointers: