You are required to have an API key to use rdpla. To get one,
use dpla_get_key for getting a key programatically.
After getting the key, you can pass the key as a parameter to rdpla
functions, but we recommend storing the key on your machine, since not
exposing your key in your files that may end up on the web is good
practice. Store your key either as an environment variable in your
.Renviron file or similar like DPLA_API_KEY=<yourkey>,
or as an R option in your .Rprofile file like
options(dpla_api_key = "<yourkey>"). Either will be read in
when you call rdpla functions. Make sure to restart your R session
after storing your key as either env var or R option.