Do you see a # character at the end of the command line prompt?
You are not upgrading with ‘apt upgrade’
If you have not changed directory since you downloaded with wget you can also try:
./hst-install.sh instead of using bash (since you already did chmod on the file)
Please share a screenshot so we can understand what is going on and we don’t have to shoot in the dark to help you
In the meantime, I was able to solve the problem. I installed a Debian 11 server by hand instead of using a ready-made image. Now the installation of HestiaCP works without problems.