Hey!
I was doing all that stuff man this is crazy took me ages but look this is what you need:
ENABLE SSH so you can use the command line!!
magento 2 is supouse to run everything from that CLI.
Install winSCP in your PC, connetc to your SFTP connect do the whole steps until you can use te CL. after that guess what all you need to do toenable maintenance is type:
php bin/magento maintenance:enable
thats it.
here is a list of all the commands
https://firebearstudio.com/blog/magento-2-command-line-tool-binmagento.html
Accept this as solved!