Problem with package installation

Good morning. I have a problem when installing new packages, something that didn't happen before. This is the example of the psych package in a Rmarkdown:

install.packages("psych")

library(psych)

Response:
Installing package into ‘/opt/R/4.0.3/lib/R/library_shared’
(as ‘lib’ is unspecified)
Warning in install.packages :
'lib = "/opt/R/4.0.3/lib/R/library_shared"' is not writable

The background jobs says the following:
Show in new window
Installing the package in '/opt/R/4.0.3/lib/R/library_shared' (since 'lib' is not specified).
(since 'lib' is not specified)
Warning in install.packages :
'lib = "/opt/R/4.0.3/lib/R/library_shared"' is not writable.
Installing 'psych' ...
Installing the package in '/opt/R/4.0.3/lib/R/library_shared' (since 'lib' is not writable)
(since 'lib' is not specified)
Warning in utils::install.packages("psych", repos = "https://cran.rstudio/") :
lib = "/opt/R/4.0.3/lib/R/library_shared"' not writable
Error in utils::install.packages("psych", repos = "https://cran.rstudio.com/") :
can't install packages
Callback: sourceWithProgress -> eval -> eval ->
Interrupted execution

I'm having a really hard time finding a solution.

You don't have write permissions on this folder, either change your user's permissions accordingly or set set your package library in a folder where you have write permissions.

You can change the default library folder by setting your R_LIBS_SITE environmental variable in a .Reviron or .Rprofile file. For example:

# In a .Renviron file you can set it by adding a line like this one with the desired location 
R_LIBS_SITE="C:\\Program Files\\R\\R-4.1.2\\library"

For a more detailed explanation, you can read this blog post

It is now solved. Thank you very much for your time and great explanation. See you soon.