What @kisun said - if your system language or keyboard layout is not english.
If that’s the case you could figure out a way to type your password as if you where typing on an english layout keyboard
or
simply reinstall and choose a password which you can type as if your keyboard was in english.
After first boot you can adjust the keyboard layout - and change the password to something else - but the installer doesn’t let you do it if your language is not english.