Isso funcionou para mim:
#!/usr/bin/env bash
url='https://www.vpnbook.com/freevpn'
html=$( curl -# -L "${url}" 2> '/dev/null' )
username=$(
<<< "${html}" \
grep -P -o -e '(?<=<li>Username: <strong>)(.*?)(?=<\/strong><\/li>)' |
head -n 1
)
password=$(
<<< "${html}" \
grep -P -o -e '(?<=<li>Password: <strong>)(.*?)(?=<\/strong><\/li>)' |
head -n 1
)
printf '%s\n' "Username: ${username}" "Password: ${password}"