我已经按照此处的说明进行操作了
https://cran.r-project.org/bin/windows/Rtools/
当我在jsonlite包上运行测试时，我仍然得到
WARNING: Rtools is required to build R packages but is not currently installed. Please download and install the appropriate version of Rtools before proceeding:
然后
Error: ERROR: no permission to install to directory 'C:/Users/fl014036/Documents/R/R-3.6.2/library'
Warning in install.packages :
installation of package ‘jsonlite’ had non-zero exit status