Instalação do R markdown

Estou tendo problemas para instalar o Rmarkdown.
Logo no início da mensagem o R avisa que é necessário instalar o Rtool, então eu instalei. Mas continuo recebendo a mesma mensagem.
Depois, na instalação do pacote "tinytex", quando o R vai preparar o pacote para "lazy loading" acontece um erro.

Alguém pode me ajudar?

A mensagem é a seguinte:


> install.packages("rmarkdown")
WARNING: Rtools is required to build R packages but is not currently installed. Please download and install the appropriate version of Rtools before proceeding:

https://cran.rstudio.com/bin/windows/Rtools/
Installing package into ‘C:/Users/Jessica/Documents/R/win-library/3.6’
(as ‘lib’ is unspecified)
also installing the dependencies ‘xfun’, ‘tinytex’


There are binary versions available but the source versions are
later:
binary source needs_compilation
xfun 0.22 0.29 TRUE
tinytex 0.31 0.35 FALSE
rmarkdown 2.8 2.11 FALSE

Binaries will be installed
trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.6/xfun_0.22.zip'
Content type 'application/zip' length 323923 bytes (316 KB)
downloaded 316 KB

package ‘xfun’ successfully unpacked and MD5 sums checked

The downloaded binary packages are in
C:\Users\Jessica\AppData\Local\Temp\RtmpqaYPd2\downloaded_packages
installing the source packages ‘tinytex’, ‘rmarkdown’

trying URL 'https://cran.rstudio.com/src/contrib/tinytex_0.35.tar.gz'
Content type 'application/x-gzip' length 30624 bytes (29 KB)
downloaded 29 KB

trying URL 'https://cran.rstudio.com/src/contrib/rmarkdown_2.11.tar.gz'
Content type 'application/x-gzip' length 3212367 bytes (3.1 MB)
downloaded 3.1 MB

* installing *source* package 'tinytex' ...
** package 'tinytex' successfully unpacked and MD5 sums checked
** using staged installation
** R
** inst
** byte-compile and prepare package for lazy loading
Error in loadNamespace(j <- i[[1L]], c(lib.loc, .libPaths()), versionCheck = vI[[j]]) :
namespace 'xfun' 0.22 is being loaded, but >= 0.23 is required
Calls: <Anonymous> ... namespaceImportFrom -> asNamespace -> loadNamespace
Execução interrompida
ERROR: lazy loading failed for package 'tinytex'
* removing 'C:/Users/Jessica/Documents/R/win-library/3.6/tinytex'
Warning in install.packages :
installation of package ‘tinytex’ had non-zero exit status
ERROR: dependency 'tinytex' is not available for package 'rmarkdown'
* removing 'C:/Users/Jessica/Documents/R/win-library/3.6/rmarkdown'
Warning in install.packages :
installation of package ‘rmarkdown’ had non-zero exit status

The downloaded source packages are in
‘C:\Users\Jessica\AppData\Local\Temp\RtmpqaYPd2\downloaded_packages’

Já resolvi. Meu R estava desatualizado. Quando instalei a versão mais nova consegui instalar o Rmarkdown.