Solved
Installation problem
After the whole process at the end the software doesn't get installed, it just appeared "unsuccessful" and doesn't download.
There was a similar question before - "Error during Installation - Error at 1%": https://community.ptc.com/t5/Mathcad-Installation/Error-during-Installation-Error-at-1/m-p/725131
P.S. And article - "Error "Some applications failed or cancelled Click information icon of failed applications for details"": https://www.ptc.com/en/support/article/CS290899