Hi @AT_AYX sorry for the delayed response!
Do you have the Admin version of Alteryx? I just ran the update.packages() command on my machine and didn't get your error, so these steps seemed to work:
Firstly navigate to this R.exe: - "C:\Program Files\Alteryx\R-4.0.4\bin\R.exe"
Then right click it and 'run as administrator',
Then type in 'update.packages()' and hit 'y/n' for the packages until you reach Rcpp (where you should hit 'y').
Then let it do its thing.
If you've got the local version, then I think you'll need to navigate to the 'R.exe' in "C:\Users\[User]\AppData\Roaming\Alteryx" (I can't remember exactly where in there it is I'm afraid).
If you didn't want to do the update.packages(), then deleting the 'Rcpp' folder in either
"C:\Program Files\Alteryx\R-4.0.4\library" (admin) or
and then install it to that location again either using the R.exe mentioned above, or the Install R packages app available here: [link]
Hope that helps!