Can not knit to pdf: Error message when downloading / installing tinytex

[MB1]

When I download tinytex and install it with:

install.packages('tinytex')
tinytex::install_tinytex()

I get the following warning:

Warnmeldungen:
1: In download.file(url, output, ..., method = method) :
  heruntergeladene Länge 37748736 != angegebene Länge 64858129
2: In download.file(url, output, ..., method = method) :
  URL 'https://appveyorcidatav2.blob.core.windows.net/yihui-27038/tinytex/1-0-1305/j63v9wfqn5pa2i1n/TinyTeX-1.tgz?sv=2015-12-11&sr=c&sig=lXJnJqUS4Z20e6kjbynFUBUPf4Z4tKtIaOBh8vAQCKI%3D&st=2020-12-08T09%3A53%3A43Z&se=2020-12-08T09%3A59%3A43Z&sp=r': Timeout of 60 seconds was reached
3: In download.file(url, output, ..., method = method) :
  heruntergeladene Länge 35258368 != angegebene Länge 64858129
4: In download.file(url, output, ..., method = method) :
  URL 'https://appveyorcidatav2.blob.core.windows.net/yihui-27038/tinytex/1-0-1305/j63v9wfqn5pa2i1n/TinyTeX-1.tgz?sv=2015-12-11&sr=c&sig=C1zUuBSIaiMP9Jjbd%2BR%2FMdAVA7E5rpAH2MLOIW%2FkjyU%3D&st=2020-12-08T09%3A54%3A43Z&se=2020-12-08T10%3A00%3A43Z&sp=r': Timeout of 60 seconds was reached

tinytex:::is_tinytex() says TRUE.

But when I want to knit a simple Rmd.file to pdf

---
output:
  pdf_document:
    latex_engine: xelatex
    keep_tex: yes
---


# Title

Text

I get the following error message:

! Undefined control sequence.
l.4 \hypertarget
                {title}{% 

I speculated it has something to do with rmarkdown and reverted back to an older version of rmarkown (1.7), but this did not help.

I am now wondering if the above warning message has something to do with the problem.

Here are my system infos:

> xfun::session_info()
R version 4.0.3 (2020-10-10)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Catalina 10.15.7, RStudio 1.4.933

Locale: de_DE.UTF-8 / de_DE.UTF-8 / de_DE.UTF-8 / C / de_DE.UTF-8 / de_DE.UTF-8

Package version:
  base64enc_0.1.3 compiler_4.0.3  digest_0.6.27   evaluate_0.14   glue_1.4.2     
  graphics_4.0.3  grDevices_4.0.3 highr_0.8       htmltools_0.5.0 jsonlite_1.7.1 
  knitr_1.30      magrittr_2.0.1  markdown_1.1    methods_4.0.3   mime_0.9       
  rlang_0.4.9     rmarkdown_2.4.5 stats_4.0.3     stringi_1.5.3   stringr_1.4.0  
  tinytex_0.27    tools_4.0.3     utils_4.0.3     xfun_0.19       yaml_2.2.1