You can activate password protection using .htaccess and .htpassword files. You can generate .htpassword file using this generator.

.htaccess

AuthUserFile /home/ftp-username/public_html/.htpasswd AuthGroupFile None AuthName "Login required" AuthType Basic require valid-user

.htpasswd

login-name:$apr1$ew1zoXvl$MEVdT65xPMA.75v9f0h2D/

Save the .htaccess file using notepad or other text editor. Name must be “.htaccess” not “.htaccess.txt”. Upload both files to your FTP server.