I need to set up supporter but it is not working

I followed the instructions for supporter and put it into an mu-plugins folder which I created. I put the mu-plugins folder into PLUGINS - wpcontent/plugins/mu-plugins - and everything seemed to work ok - or at least it showed up in my admin.

When I re-read the instructions this morning I noticed it should have gone outside of the PLUGINS folder and into wpcontent/mu-plugins so I changed it and when I did that the whole thing disappears and does not show up in the network admin under plugins anymore. All of them were deactivated and have disappeared.

The subscriptions.php that I added under wp-admin shows up in the network admin area and I can set the cost of becoming a member but nothing else.

The whole site will be a paid membership site. People can register for free and I will add a few things for them to download/watch to get them thinking about their blog, and I will have one free part of the buddy forum for questions. Outside of that its all supporter access only

I seem to have some gaps in getting my paid network setup and would appreciate some help around where this folder should go.

Once this is setup is there a code I have to add to the signup page to get the form to show up?

I have a ton more questions but will start by sorting this one out first before asking any more.

thank you