Thank you for your great help and your patience. I did as you say. The process starts with this message, in yellow:

The directory '/home/julio/.cache/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/home/julio/.cache/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.

Process ends with this message:

ompilation terminated.
error: command 'x86_64-linux-gnu-gcc' failed with exit status 1

----------------------------------------

Command "/usr/bin/python3 -u -c "import setuptools, tokenize;file='/tmp/pip-build-uumczq4y/scrypt/setup.py';f=getattr(tokenize, 'open', open)(file);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, file, 'exec'))" install --record /tmp/pip-o2nmvx3c-record/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /tmp/pip-build-uumczq4y/scrypt/