Please explain the problem in detail. What happens? What is/are the exact error message(s) ?

Are you saying you tried to download Firefox, but got a warning message? Please translate the message you got.

Did you get the full installer from; Download Firefox For All languages And Systems {web link}

Are you saying you tried to download Firefox, but got a warning message? Yes

После установки 10.0.19044.1288 писало ошибку.

Firefox installer.exe заблокирована, так как этот файл может причинить вред вашему устройству.

Не помню, долго лазил снимал галочки. Загрузил.

translate

After installing 10.0.19044.1288 wrote an error.

Firefox installer.exe is blocked because this file may harm your device.

I don’t remember, I climbed for a long time and removed the check marks. Loaded.

Is the problem solved? Please explain what you did. Then flag that post as Solved Problem as this can help others with similar problems.